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Sichuan peppercorn Zanthoxylum sp. is an important food condiment, currently used in East Asia and South Asia. In this paper, we review genetic, archaeological, and linguistic evidence regarding the use of Zanthoxylum by ancient human populations. The evidence from these three disciplines converge to suggest that its earliest attested use dates from the mid-fourth millennium BCE, in Western Sichuan, making it one of the oldest spices in East Asia. The paper also discusses how this spice was supplemented, and even superseded, by the introduction of the American Chili Pepper (Capsicum spp.). in the seventeenth century. We further argue that differences in the biosynthesis of numbing compounds between cultivars of Zanthoxylum sp. in northern and southern Western China that are due to deep evolutionary processes may have in turn influenced culinary preferences.

The COVID-19 pandemic offered humanity a portal through which we could break with the past and imagine our world anew. This article reviews how over the course of 2020, a series of intersecting crises at the nexus of racism, settler colonialism, climate change, and sexual harassment have prompted acts of resistance and care in the field of archaeology. Throughout the article, we provide concrete suggestions as to how we can continue the work of movements begun over the course of the past year to improve dynamics within our field and use the lessons from our field to improve life for all people in the world and for our planet. [La pandemia de COVID‐19 ofreció a la humanidad un portal a través del cual podemos romper con el pasado e imaginar nuestro mundo de nuevo. Este artículo revisa cómo sobre el curso de 2020, una serie de crisis que se intersecan en la concatenación de racismo, colonialismo de poblamiento, cambio climático y acoso sexual han incitado actos de resistencia y cuidado en el campo de la arqueología. A lo largo del artículo, proveemos sugerencias concretas en cuanto a cómo podemos continuar el trabajo de los movimientos empezado en el transcurso del año pasado para mejorar la dinámica dentro de nuestro campo y el uso de lecciones de nuestro campo para mejorar la vida de todas las personas en el mundo y de nuestro planeta. [

The transition between the Majiayao (5300–4000 BP) and Qijia (4200–3500 BP) “cultures” in what is now northwestern China’s Gansu Province has typically been defined by major technological changes in pottery forms, subsistence practices, and site locations. These changes are thought to have been driven by a combination of climate change induced cooling and drying as well as human migration into the region from areas further east. Based on our review of literature on the topic, as well as recent fieldwork in the northern Tao River Valley, we suggest that the picture is significantly more complex, with some new technologies slowly being experimented with, adopted, or rejected, while many other aspects of production and social organization persisted over hundreds of years. We hypothesize that these changes reflect the active agency of the inhabitants of southern Gansu during the fifth and fourth millennia BP balancing long-standing cultural traditions with influxes of new technologies. Unlike some societies in other regions at this time, however, increasing technological specialization does not appear to have resulted in growing social inequality, but the archaeological material instead reflects increasingly complex heterarchical organization.

Paleoethnobotanical assemblages from the Northwestern region of North America often yield geophyte subterranean organs, but these carbonized remains are difficult to identify to species or genus level. We examine 11 species (8 genera) of the most ethnographically prevalent Northwest geophyte foods for macro- and micro-morphologic geophyte features, with a focus on bulbs from the Asparagales and Liliales orders. In this contribution, we discuss ethnographic practices which may affect archaeological material and provide digital photographic and quantitative references for both fresh and carbonized geophytes. We determine that pavement epidermal cells are the most diagnostic criteria for identifying bulbs in paleoethnobotanical assemblages. These identification standards provide researchers with comparative material to address questions of plant use, preparation, and stewardship across the greater Northwest Coast and Columbia-Fraser Plateau cultural and geographic regions.

Little is known about the prehistoric domestication and cultivation of crops in the Eastern Himalayas (eastern Nepal, Bhutan, Sikkim, Arunachal Pradesh), due to a lack of archaeological and archaeobotanical research in the area. This paper reconstructs the lexical terminology for grains in the East Bodish language sub-family in Eastern Bhutan. Historical linguistic methods suggest that the immediate ancestors of the modern East Bodish speakers cultivated buckwheat (Fagopyrum) and barley (Hordeum) but not millets or rice. Buckwheat was traditionally thought to have been domesticated in Southwest China; however, this research reveals that cultivation (and potentially subsequent domestication) may have taken place among East Bodish language speakers or their ancestors. These findings also pose a challenge for studies which seek to reconstruct millets to ancestral Tibeto-Burman speaking populations.

In prehistoric coastal and western-central Thailand, rice was the dominant cultivar. In eastern-central Thailand, however, the first known farmers cultivated millet. Using one of the largest collections of archaeobotanical material in Southeast Asia, this article examines how cropping systems were adapted as domesticates were introduced into eastern-central Thailand. The authors argue that millet reached the region first, to be progressively replaced by rice, possibly due to climatic pressures. But despite the increasing importance of rice, dryland, rain-fed cultivation persisted throughout ancient central Thailand, a result that contributes to refining understanding of the development of farming in Southeast Asia.

Rice (Oryza sativa) is one of the world's most important food crops, and is comprised largely of japonica and indica subspecies. Here, we reconstruct the history of rice dispersal in Asia using whole-genome sequences of more than 1,400 landraces, coupled with geographic, environmental, archaeobotanical and paleoclimate data. Originating around 9,000 yr ago in the Yangtze Valley, rice diversified into temperate and tropical japonica rice during a global cooling event about 4,200 yr ago. Soon after, tropical japonica rice reached Southeast Asia, where it rapidly diversified, starting about 2,500 yr BP. The history of indica rice dispersal appears more complicated, moving into China around 2,000 yr BP. We also identify extrinsic factors that influence genome diversity, with temperature being a leading abiotic factor. Reconstructing the dispersal history of rice and its climatic correlates may help identify genetic adaptations associated with the spread of a key domesticated species.

Archaeological research has documented the migration of Neolithic farmers onto the Tibetan Plateau by 4000 BC. How these incoming groups interacted, if at all, with local indigenous foragers, however, remains unclear. New archaeobotanical and zooarchaeological data from the Zongri site in the north-eastern Tibetan Plateau suggest that local foragers continued to hunt but supplemented their diet with agricultural products in the form of millet. The authors propose that, rather than being grown locally, this millet was acquired via exchange with farmers. This article highlights how indigenous foragers engaged in complex patterns of material and cultural exchange through encounters with newly arrived farmers.

Yak, a species of bovid uniquely adapted to high-altitude environments, plays a critical role in the life of the inhabitants of the Tibetan Plateau and neighboring areas. There is currently no consensus on when these animals may have been domesticated. In this paper, we review the archaeological, genetic, and linguistic evidence relevant to this question, and suggest that the domestication took place following hybridization with taurine cattle from the end of the fourth millennium BCE. This study also shows that the original domesticators of yaks included not only the ancestors of the Tibetans, but also Rgyalrongic speaking people from Eastern Tibet.

Earth ovens, hearths, and middens are common archaeological features in western North America that contain the residues of everyday activities. Ethnographic and archaeological research indicates these in-ground food preparation features were frequently reused over many months and years. These quotidian features therefore can be productively thought of as having use-lives or biographies. Here we present a framework for interpreting these archaeological food preparation feature biographies and the palimpsest nature of earth oven features. We illustrate the value of this framework through paleoethnobotanical analysis of archived soil samples from a bulk food processing site on the Columbia-Fraser Plateau in northeastern Washington State. While this site and other food preparation sites throughout the Plateau are largely interpreted as remains of intensive geophyte processing, our finds indicate that a wide range of economic plants were processed at this location, indicative of a dynamic and flexible subsistence system. We suggest that residents and visitors to the Pend Oreille Valley from ca. 2700-500 cal BP frequently returned to and reused earth oven features as they processed multiple plant food taxa including nodding onion (Allium cernuum), camas (Camassia quamash) goosefoot chenopod seeds (cf. Chenopodium atrovirens), and pine nuts (Pinus spp.). We see a biographical approach as a potential solution to the common “palimpsest problem” and suggest this framework may be a fruitful way of investigating multiple food preparation recipes, methods, and events, as well as adding paleoenvironmental datasets to biographical or life-history archaeological rhetoric.

The dispersal of rice (Oryza sativa) following domestication influenced massive social and cultural changes across South, East, and Southeast (SE) Asia. The history of dispersal across islands of SE Asia, and the role of Taiwan and the Austronesian expansion in this process remain largely unresolved. Here, we reconstructed the routes of dispersal of O. sativa ssp. japonica rice to Taiwan and the northern Philippines using whole-genome resequencing of indigenous rice landraces coupled with archaeological and paleoclimate data. Our results indicate that japonica rice found in the northern Philippines diverged from Indonesian landraces as early as 3,500 years before present (BP). In contrast, rice cultivated by the indigenous peoples of the Taiwanese mountains has complex origins. It comprises two distinct populations, each best explained as a result of admixture between temperate japonica that presumably came from northeast Asia, and tropical japonica from the northern Philippines and mainland SE Asia, respectively. We find that the temperate japonica component of these indigenous Taiwan populations diverged from northeast Asia subpopulations at about 2,600 BP, whereas gene flow from the northern Philippines had begun before ∼1,300 BP. This coincides with a period of intensified trade established across the South China Sea. Finally, we find evidence for positive selection acting on distinct genomic regions in different rice subpopulations, indicating local adaptation associated with the spread of japonica rice.

Since the last systematic review of Tibetan archaeology in 2004 published in Journal of World Prehistory (Aldenderfer and Zhang 2004), a revival of archaeological research on the plateau has begun to reshape our understanding of key issues such as when the plateau was first permanently occupied by humans, and when and how Tibetans first adopted the farming and pastoral systems that characterize the plateau today. Understanding who the first Tibetans were, and how they adapted to this high-altitude environment, both genetically and culturally, have been central themes of recent research on the plateau. We review these developments and place them into a wider regional framework with a focus on the better-known eastern Tibetan Plateau.

This project considered the deposition history of a burned structure located on the Kalispel Tribe of Indians ancestral lands at the Flying Goose site in northeastern Washington. Excavation of the structure revealed stratified deposits that do not conform to established Columbia Plateau architectural types. The small size, location, and absence of artifacts lead us to hypothesize that this site was once a non-domestic structure. We tested this hypothesis with paleoethnobotanical, bulk geoarchaeological, thin section, and experimental firing data to deduce the structural remains and the post-occupation sequence. The structure burned at a relatively low temperature, was buried soon afterward with imported rubified sediment, and was exposed to seasonal river inundation. Subsequently, a second fire consumed a unique assemblage of plant remains. Drawing on recent approaches to structured deposition and historic processes, we incorporate ethnography to argue that this structure was a menstrual lodge. These structures are common in ethnographic descriptions, although no menstrual lodges have been positively identified in the archaeological record of the North American Pacific Northwest. This interpretation is important to understanding the development and time depth of gendered practices of Interior Northwest groups.

Increasing the productivity and yield of rice in Central Thailand has been a key focus of international and local government policy. Efforts have centered around producing a second winter season of irrigated rice. However, a series of droughts in the region have led to widespread crop failure. We carry out a re-evaluation of weather station and environmental data and combine this with new information from a key archeological site in Central Thailand, Phromthin Tai, whose occupation covers a long and critical period of Thai prehistory. Based on these data, we argue that farmers in the area employed an adaptive and resilient agricultural and wild-plant-food-based subsistence system that was adapted to the region’s high variability in rainfall. This subsistence system bridged the divide between the wild and cultivated and between wet and dry farming. The temporal and spatial diversity inherent in this system makes it vulnerable to destruction by agricultural policies that focus singly on improving yields.

The Asian monsoon and associated river systems supply the water that sustains a large portion of humanity, and has enabled Asia to become home to some of the oldest and most productive farming systems on Earth. This book uses climate data and environmental models to provide a detailed review of variations in the Asian monsoon since the mid-Holocene, and its impacts on farming systems and human settlement. Future changes to the monsoon due to anthropogenically-driven global warming are also discussed. Faced with greater rainfall and more cyclones in South Asia, as well as drying in North China and regional rising sea levels, understanding how humans have developed resilient strategies in the past to climate variations is critical. Containing important implications for the large populations and booming economies in the Indo-Pacific region, this book is an important resource for researchers and graduate students studying the climate, environmental history, agronomy and archaeology of Asia.

The Khao Wong Prachan Valley of central Thailand is one of four known prehistoric loci of copper mining, smelting and casting in Southeast Asia. Many radiocarbon determinations from bronze-consumption sites in north-east Thailand date the earliest copper-base metallurgy there in the late second millennium BC. By applying kernel density estimation analysis to approximately 100 new AMS radiocarbon dates, the authors conclude that the valley's first Neolithic millet farmers had settled there by c. 2000 BC, and initial copper mining and rudimentary smelting began in the late second millennium BC. This overlaps with the established dates for Southeast Asian metal-consumption sites, and provides an important new insight into the development of metallurgy in central Thailand and beyond.

Farmer's ability to rapidly grow their populations has been seen as an advantage in allowing them to either engulf or simply do away with foragers. Research on agriculture's spread in East Asia has followed an underlying assumption: that farming produced equally reliable returns across the vast expanse of territories into which it spread. Farmers are thus always seen as being at a demographic advantage. However, in some parts of Asia, ecological barriers to growing crops may have meant that the opposite was true. In order to illuminate how foragers and farmers might have interacted in environments marginal to crop cultivation, I argue that we first need to outline where the barriers to farmer expansion in prehistory lay. Using ecological niche modeling combined with an analysis of recent archaeological data, this paper contrasts forager farmer interaction in two different areas of the Tibetan Plateau. It argues that the higher elevation reaches of the “third pole” constituted a barrier for early millet farmers expanding into the region. In these areas foragers may have maintained a competitive advantage.

We describe a preliminary survey of a relatively unknown part of the eastern Himalayas: northwestern Sichuan. This survey revealed that three phases of occupation are represented across the landscape. Large settlements with dense remains characterize the landscape during the Neolithic (3400–2000 cal b.c.). Following a hiatus in occupation, stone-cist graves characterize the region during the Bronze Age (1450–800 cal b.c.). The lack of settlement remains from this period indicates that mobile pastoralism increased in importance. Finally, between a.d. 500 and 1500, dense scatters of ceramics over a wide altitudinal range correspond to a fragmentation in Tibetan history, when local warlords established themselves in the region. While some changes in occupation and subsistence practices are linked to climate change, others relate to changes in political power. We argue that further survey work is needed to expand our understanding of past land use and the development of pastoralist practices.

Asking the public to question the assumption that our current systems of governance and food production represent the apex of an evolutionary trajectory is timely and well warranted.

Rice (Oryza sativa) is one of the world’s most important food crops. We reconstruct the history of rice dispersal in Asia using whole-genome sequences of >1,400 landraces, coupled with geographic, environmental, archaeobotanical and paleoclimate data. We also identify extrinsic factors that impact genome diversity, with temperature a leading abiotic factor. Originating ∼9,000 years ago in the Yangtze Valley, rice diversified into temperate and tropical japonica during a global cooling event ∼4,200 years ago. Soon after, tropical rice reached Southeast Asia, where it rapidly diversified starting ∼2,500 yBP. The history of indica rice dispersal appears more complicated, moving into China ∼2,000 yBP. Reconstructing the dispersal history of rice and its climatic correlates may help identify genetic adaptation associated with the spread of a key domesticated species.One sentence summaryWe reconstructed the ancient dispersal of rice in Asia and identified extrinsic factors that impact its genomic diversity.

By documenting how humans adapted to changes in their environment that are often much greater than those experienced in the instrumental record, archaeology provides our only deep-time laboratory for highlighting the circumstances under which humans managed or failed to find to adaptive solutions to changing climate, not just over a few generations but over the longue durée . Patterning between climate-mediated environmental change and change in human societies has, however, been murky because of low spatial and temporal resolution in available datasets, and because of failure to model the effects of climate change on local resources important to human societies. In this paper we review recent advances in computational modeling that, in conjunction with improving data, address these limitations. These advances include network analysis, niche and species distribution modeling, and agent-based modeling. These studies demonstrate the utility of deep-time modeling for calibrating our understanding of how climate is influencing societies today and may in the future.

Recent archeological evidence has revealed that a major transition in subsistence regimes took place around the second millennium BC. This paper argues that in order for archeologists to understand transitions in subsistence regimes in the past, it is necessary to develop models capable of outlining our frames of reference. It summarizes how ecological niche models (ENM) have contributed to our understanding of the spread of agriculture to the Plateau and situates ENM within the two current paradigms used for understanding subsistence change in archeological research (Optimal Foraging Theory and Niche Construction Theory) and argues that recent advances in computing and in spatial modeling should be employed by researchers seeking to make testable hypothesis about subsistence change on the Tibetan Plateau.

This paper explores how changes in sea level and biome distribution may have affected the habitats occupied by hunter-gatherers in East Asia. Using a model-based reconstruction of changing sea level from the Last Glacial Maximum (LGM) to present day, our analysis reveals that the exposure of a large continental shelf during the LGM sea level lowstand created a wealth of wooded, estuarine, and coastal biomes that could have been exploited intensively by Late Pleistocene hunter-gatherers. Models explaining hunter-gatherer subsistence changes and migrations in this period should take into account the large area that has been lost to rising sea level since the LGM.

Agrarian societies reduced risk during pan-Asian cooling events by investing in pastoralism and developing long-distance trade., Ancient farmers experienced climate change at the local level through variations in the yields of their staple crops. However, archaeologists have had difficulty in determining where, when, and how changes in climate affected ancient farmers. We model how several key transitions in temperature affected the productivity of six grain crops across Eurasia. Cooling events between 3750 and 3000 cal. BP lead humans in parts of the Tibetan Plateau and in Central Asia to diversify their crops. A second event at 2000 cal. BP leads farmers in central China to also diversify their cropping systems and to develop systems that allowed transport of grains from southern to northern China. In other areas where crop returns fared even worse, humans reduced their risk by increasing investment in nomadic pastoralism and developing long-distance networks of trade. By translating changes in climatic variables into factors that mattered to ancient farmers, we situate the adaptive strategies they developed to deal with variance in crop returns in the context of environmental and climatic changes.

New data from the Tibetan Plateau allow us to understand how populations dealt with the challenges of moving crops into altitudinally constrained environments. Despite the interest in explaining the timing and the mechanisms via which agricultural products spread to the roof of the world, current models for the spread of agriculture to this region have been simplistic and the presence of crop domesticates is often straightforwardly interpreted as indicating the existence of an agricultural system at the site. This is largely due to a fundamental lack of understanding of where crops could be grown in prehistory on the Plateau. Although it has generally been assumed that moving agriculture into this area was challenging, little work has specifically addressed the constraints imposed on humans as they moved crops into this area. Employing an agro-ecological niche model, I formally model the constraints that were faced by humans as they moved a series of crops into the Tibetan Plateau between the 4th and 1st millennium cal. BC. Based on the results of this analysis, I argue that the end of the climatic optimum meant that millet agriculture was no longer a viable strategy in many parts of the Eastern Himalayas. The arrival of frost tolerant crops in the 2nd millennium BC provided new opportunities in the cooler post climatic optimum world. These models further reveal that sites that have been previously considered as engaged directly in agricultural production may have been more distantly connected to an agricultural lifestyle than previously thought.

Proso millet (Panicum miliaceum L.) is a warm season grass with a growing season of 60 to 100 days. It is a highly nutritious cereal grain used for human consumption, bird seed, and/or ethanol production. Unique characteristics, such as drought and heat tolerance, make proso millet a promising alternative cash crop for the Pacific Northwest (PNW) region of the United States. Development of proso millet varieties adapted to dryland farming regions of the PNW could give growers a much-needed option for diversifying their predominantly wheat-based cropping systems. In this review, the agronomic characteristics of proso millet are discussed, with emphasis on growth habits and environmental requirements, place in prevailing crop rotations in the PNW, and nutritional and health benefits. The genetics of proso millet and the genomic resources available for breeding adapted varieties are also discussed. Last, challenges and opportunities of proso millet cultivation in the PNW are explored, including the potential for entering novel and regional markets.

Understanding how, why and by what mechanisms agricultural practices, technologies and products spread out of their zones of original development is a central theme of archaeology. To date, very few studies have combined agro-ecological modeling with detailed analyses of archaeobotanical remains to outline the kinds of challenges that ancient humans faced as they moved crops into environments different from their original homeland of domestication. This paper employs ecological niche modeling to outline the constraints faced by ancient humans as they moved rice, millets and eventually wheat and barley into the mountainous region of Southwest China. In particular, we propose that moving rice into this region presented considerable challenges for its cultivators and we infer that its spread into this area was facilitated by breeding cold adapted varieties of rice or by combining its cultivation with that of millet. High altitude areas did not take up full-scale agriculture until the introduction of cold adapted western Eurasian domesticates such as wheat and barley. The temperature niche models reinforce the adoption of these regionally varied agricultural strategies and support the significance of domesticates other than rice for the spread of agriculture into Southwest China.

The Chengdu plain of south-west China lies outside the main centres of early domestication in the Huanghe and Yangzi valleys, but its importance in Chinese prehistory is demonstrated by the spectacular Sanxingdui bronzes of the second millennium BC and by the number of walled enclosures of the third millennium BC associated with the Baodun culture. The latter illustrate the development of social complexity. Paradoxically, however, these are not the outcome of a long settled agricultural history but appear to be associated with the movement of the first farming communities into this region. Recent excavations at the Baodun type site have recovered plant remains indicating not only the importance of rice cultivation, but also the role played by millet in the economy of these and other sites in south-west China. Rice cultivation in paddy fields was supplemented by millet cultivation in neighbouring uplands. Together they illustrate how farmers moving into this area from the Middle Yangzi adjusted their cultivation practices to adapt to their newly colonised territories.

Rowan Flad, Timothy Horsley, Jade d'Alpoim Guedes, Gwen Bennett, Shuicheng Li, Zhanghua Jiang, Jiang Ming & He Kunyu (2014). Survey, Excavation and Geophysics at Songjiaheba – A Small Bronze Age Village in the Chengdu Plain. Asian Perspectives (52) 1: 119-142.

The timing and mechanics of the spread of agriculture to the Tibetan Plateau—one of the most challenging environmental contexts on earth—is a focus of recent work and debate. Understanding the timing and spread of agriculture is basic to archaeology and history worldwide. Researchers seek evidence for the earliest, furthest, or highest occurrences of diagnostic elements. However, the Tibetan Plateau case illustrates a key flaw in current work: archaeologists have often uncritically interpreted the presence of plant domesticates at archaeological sites as being indicative of local agricultural practice. This assumption neglects the long history of food exchange on the Plateau, as elsewhere in the world, even beyond what were then the limits of agriculture. The cause is a fundamental lack of understanding of where crops could be grown in prehistory. Using a formal model of the agricultural thermal niche between the 5500 BP and the present, we argue that agricultural niches on the Tibetan Plateau were tightly constrained to lower-elevation river valleys throughout time. This pattern is confirmed by analysis of the extent of modern crop production on the Plateau. The challenges deriving from these altitudinal constraints placed on early Tibetans largely explain how and why the Tibetan economy developed in the way that it did.

The timing and mechanics of the spread of agriculture to the Tibetan Plateau—one of the most challenging environmental contexts on earth—is a focus of recent work and debate. Understanding the timing and spread of agriculture is basic to archaeology and history worldwide. Researchers seek evidence for the earliest, furthest, or highest occurrences of diagnostic elements. However, the Tibetan Plateau case illustrates a key flaw in current work: archaeologists have often uncritically interpreted the presence of plant domesticates at archaeological sites as being indicative of local agricultural practice. This assumption neglects the long history of food exchange on the Plateau, as elsewhere in the world, even beyond what were then the limits of agriculture. The cause is a fundamental lack of understanding of where crops could be grown in prehistory. Using a formal model of the agricultural thermal niche between the 5500 BP and the present, we argue that agricultural niches on the Tibetan Plateau were tightly constrained to lower-elevation river valleys throughout time. This pattern is confirmed by analysis of the extent of modern crop production on the Plateau. The challenges deriving from these altitudinal constraints placed on early Tibetans largely explain how and why the Tibetan economy developed in the way that it did.

Difficulty in accessing high quality reference materials has been a limiting factor in the advancement of archaeobotanical research. However, new developments in online open source content management technology and faster downloading capabilities make high quality and low cost dynamic online curation of archaeobotanical reference images increasingly feasible. We describe the establishment of Paleobot.org, an open access online reference collection database for macrobotanical, microbotanical and isotopic data to help standardize and improve the identification of archaeobotanical remains.

Chen et al. (Reports, 16 January 2015, p. 248) argued that early Tibetan agriculturalists pushed the limits of farming up to 4000 meters above sea level. We contend that this argument is incompatible with the growing requirements of barley. It is necessary to clearly define past crop niches to create better models for the complex history of the occupation of the plateau.

We report directly dated evidence from circa 1400 calibrated years (cal) B.C. for the early use of wheat, barley, and flax as staple crops on the borders of the Tibetan Plateau. During recent years, an increasing amount of data from the Tibetan Plateau and its margins shows that a transition from millets to wheat and barley agriculture took place during the second millennium B.C. Using thermal niche modeling, we refute previous assertions that the ecological characteristics of wheat and barley delayed their spread into East Asia. Rather, we demonstrate that the ability of these crops to tolerate frost and their low growing degree-day requirements facilitated their spread into the high-altitude margins of western China. Following their introduction to this region, these crops rapidly replaced Chinese millets and became the staple crops that still characterize agriculture in this area today.