By sequencing 523 ancient humans, we show that the primary source of ancestry in modern South Asians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia. After the Indus Valley Civilization’s decline, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India. Simultaneously, they mixed with descendants of Steppe pastoralists who, starting around 4000 years ago, spread via Central Asia to form the other main ancestral population. The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the distinctive features shared between Indo-Iranian and Balto-Slavic languages.

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Before 3000 BC, societies of western Asia were cultivating wheat and societies of China were cultivating broomcorn millet; these are early nodes of the world's agriculture. The authors are searching for early cereals in the vast lands that separate the two, and report a breakthrough at Begash in south-east Kazakhstan. Here, high precision recovery and dating have revealed the presence of both wheat and millet in the later third millennium BC. Moreover the context, a cremation burial, raises the suggestion that these grains might signal a ritual rather than a subsistence commodity.

Archaeological research in Central Eurasia is exposing unprecedented scales of trans-regional interaction and technology transfer between East Asia and southwest Asia deep into the prehistoric past. This article presents a new archaeobotanical analysis from pastoralist campsites in the mountain and desert regions of Central Eurasia that documents the oldest known evidence for domesticated grains and farming among seasonally mobile herders. Carbonized grains from the sites of Tasbas and Begash illustrate the first transmission of southwest Asian and East Asian domesticated grains into the mountains of Inner Asia in the early third millennium BC. By the middle second millennium BC, seasonal camps in the mountains and deserts illustrate that Eurasian herders incorporated the cultivation of millet, wheat, barley and legumes into their subsistence strategy. These findings push back the chronology for domesticated plant use among Central Eurasian pastoralists by approximately 2000 years. Given the geography, chronology and seed morphology of these data, we argue that mobile pastoralists were key agents in the spread of crop repertoires and the transformation of agricultural economies across Asia from the third to the second millennium BC.

SummaryThe Eurasian 'Silk Road' is considered one the world's most extensive overland trade networks, yet questions regarding the evolution of its ancient routes and the factors that shaped their geography remain unanswered. This is especially problematic in its vast mountainous stretches, where harsh conditions and terrain are seen as impediments to travel. We present a model that uses highland pasture quality to calculate optimized seasonal herding patterns of nomadic societies, who historically