For thousands of years the Eurasian steppes have been a centre of human migrations and cultural change. Here we sequence the genomes of 137 ancient humans (about 1× average coverage), covering a period of 4,000 years, to understand the population history of the Eurasian steppes after the Bronze Age migrations. We find that the genetics of the Scythian groups that dominated the Eurasian steppes throughout the Iron Age were highly structured, with diverse origins comprising Late Bronze Age herders, European farmers and southern Siberian hunter-gatherers. Later, Scythians admixed with the eastern steppe nomads who formed the Xiongnu confederations, and moved westward in about the second or third century BC, forming the Hun traditions in the fourth-fifth century AD, and carrying with them plague that was basal to the Justinian plague. These nomads were further admixed with East Asian groups during several short-term khanates in the Medieval period. These historical events transformed the Eurasian steppes from being inhabited by Indo-European speakers of largely West Eurasian ancestry to the mostly Turkic-speaking groups of the present day, who are primarily of East Asian ancestry.

The Yamnaya expansions from the western steppe into Europe and Asia during the Early Bronze Age (~3000 BCE) are believed to have brought with them Indo-European languages and possibly horse husbandry. We analyzed 74 ancient whole-genome sequences from across Inner Asia and Anatolia and show that the Botai people associated with the earliest horse husbandry derived from a hunter-gatherer population deeply diverged from the Yamnaya. Our results also suggest distinct migrations bringing West Eurasian ancestry into South Asia before and after, but not at the time of, Yamnaya culture. We find no evidence of steppe ancestry in Bronze Age Anatolia from when Indo-European languages are attested there. Thus, in contrast to Europe, Early Bronze Age Yamnaya-related migrations had limited direct genetic impact in Asia.

Domestication of horses fundamentally transformed long-range mobility and warfare1. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling2–4 at Botai, Central Asia around 3500 bc3. Other longstanding candidate regions for horse domestication, such as Iberia5 and Anatolia6, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes, especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 bc, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMC and ZFPM1 genes. Our results reject the commonly held association7 between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe around 3000 bc8,9 driving the spread of Indo-European languages10. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium bc Sintashta culture11,12.

This paper explores the contribution of plant food to the diet of societies in Kazakhstan that are often assumed to be pastoralist. Carbon and nitrogen stable isotope analysis, together with radiocarbon dating, was carried out on human and animal bones from 24 Chalcolithic, Bronze Age, Early Iron Age, Hunic and Turkic sites across Kazakhstan. We use these data to examine dietary differences across time and space within and between populations. Our results show that at the Bronze Age sites of mountainous southern Kazakhstan people consumed C4 plants, likely domesticated millets (Panicum miliaceum or Setaria italica) and probably cultivated C3 plants (wheat or barley). By directly dating individuals with high δ 13 C values we were able to find the earliest evidence of the consumption of large quantities of millet in Central Asia to date. By contrast, there is little input of C4 plants to diets of individuals dating to the Bronze Age from northern Kazakhstan. Stable isotope data from later periods all across the region has shown that from the Early Iron Age and continuing through to the Turkic period, C4 plants were a major component of the human food web. The wide variety of stable isotope results, both within and between contemporary sites, indicates a diversity of foodways, rather than a uniform focus on pastoralism.

Steppe communities have traditionally been viewed as pastoralist groups with similar herdbased economies. Recent scholarship, however, warns against assumptions of homogeneity and new scientific techniques are providing a more nuanced approach to steppe archaeology, with increasing indications of diversity. This recent evidence further suggests that considering these communities as primarily pastoralist may hide a variety of subsistence strategies, such as fishing and cultivation. Here, we consider direct evidence for diet (in the form of stable isotope analysis) from Bronze Age communities from central Kazakhstan, in the semi-arid steppe zone. We find that the diversity recently suggested for communities across the steppe zone can be found within sites in the Karaganda region. This suggests that individuals exercised choice in their dietary habits that led to dietary differences large enough to be detectable isotopically. The results also highlight the inclusion of fish in the diet of these 'pastoral' populations, with indications that some individuals in the Final Bronze Age consumed notable amounts of millet. This shows that these 'pastoralist' economies also engaged in fishing throughout the Bronze Age, with millet cultivation becoming increasingly important in the Final Bronze Age. As such, our understanding of what it means, in this context, to be a pastoralist requires further consideration.