Indo-Aryan migrations
The Indo-Aryan migrations were the migrations into the Indian subcontinent of Indo-Aryan peoples, an ethnolinguistic group that spoke Indo-Aryan languages. These are the predominant languages of today's Bangladesh, Maldives, Nepal, North India, Pakistan, and Sri Lanka.
Indo-Aryan migration into the region, from Central Asia, is considered to have started after 2000 BCE as a slow diffusion during the Late Harappan period and led to a language shift in the northern Indian subcontinent. Several hundred years later, the Iranian languages were brought into the Iranian plateau by the Iranians, who were closely related to the Indo-Aryans.
The Proto-Indo-Iranian culture, which gave rise to the Indo-Aryans and Iranians, developed on the Central Asian steppes north of the Caspian Sea as the Sintashta culture, in present-day Russia and Kazakhstan, and developed further as the Andronovo culture.
The Indo-Aryans split off sometime between 2000 BCE and 1600 BCE from the Indo-Iranians, and migrated southwards to the Bactria–Margiana culture, from which they borrowed some of their distinctive religious beliefs and practices, but there is little evidence of genetic mingling. From the BMAC, the Indo-Aryans migrated into northern Syria and, possibly in multiple waves, into the Punjab, while the Iranians could have reached western Iran before 1300 BCE, both bringing with them the Indo-Iranian languages.
Migration by an Indo-European-speaking people was first hypothesized in the mid 17th century, by Dutch scholar Marcus Zuerius van Boxhorn, in his Scythian language and people hypothesis, to explain the linguistic similarities of the Indo-European language family, that had been identified a century earlier; he proposed a single source or origin, which was diffused by migrations from some original homeland. The language-family and migration theory were further developed, in the 18th century, by Jesuit missionary Gaston-Laurent Coeurdoux, and later East India Company employee William Jones, in 1786, through analysing similarities between European, West Asian, and South Asian languages.
This linguistic argument of this theory is supported by archaeological, anthropological, genetic, literary and ecological research. Literary research reveals similarities between various, geographically distinct, Indo-Aryan historical cultures. Ecological studies reveal that in the second millennium BCE widespread aridization led to water shortages and ecological changes in both the Eurasian steppes and the Indian subcontinent, causing the collapse of sedentary urban cultures in south central Asia, Afghanistan, Iran, and India, and triggering large-scale migrations, resulting in the merger of migrating peoples with the post-urban cultures. Comparisons of ancient DNA samples with modern South Asians populations reveal a significant infusion of male Steppe ancestry, in the second millennia BCE, with a disproportionately high contribution today present in many Brahmin and Bhumihar groups; elite populations that traditionally use an Indo-European language.
The Indo-Aryan migrations started sometime in the period from approximately 2000 to 1600 BCE, after the invention of the war chariot, and also brought Indo-Aryan languages into the Levant and possibly Inner Asia. It was part of the diffusion of Indo-European languages from the proto-Indo-European homeland at the Pontic–Caspian steppe, a large area of grasslands in far Eastern Europe, which started in the 5th to 4th millennia BCE, and the Indo-European migrations out of the Eurasian Steppes, which started approximately in 2000 BCE.
These Indo-Aryan speaking people were united by shared cultural norms and language, referred to as ārya, "noble". Diffusion of this culture and language took place by patron-client systems, which allowed for the absorption and acculturation of other groups into this culture, and explains the strong influence on other cultures with which it interacted.
Fundamentals
The Indo-Aryan migration theory is part of a larger theoretical framework. This framework explains the similarities between a wide range of contemporary and ancient languages. It combines linguistic, archaeological and anthropological research. This provides an overview of the development of Indo-European languages, and the spread of these Indo-European languages by migration and acculturation.Linguistics: relationships between languages
The linguistic part traces the connections between the various Indo-European languages, and reconstructs the proto-Indo-European language. This is possible because the processes that change languages are not random, but follow strict patterns. Sound shifts, the changing of vowels and consonants, are especially important, although grammar and the lexicon may also be significant. Historical-comparative linguistics thus makes it possible to see great similarities between related languages which at first sight might seem very different. Various characteristics of the Indo-European languages argue against an Indian origin of these languages, and point to a steppe origin.Archaeology: migrations from the steppe Urheimat
The archaeological part posits an "Urheimat" on the Pontic steppes, which developed after the introduction of cattle on the steppes around 5,200 BCE. This introduction marked the change from foragist to pastoralist cultures, and the development of a hierarchical social system with chieftains, patron-client systems, and the exchange of goods and gifts. The oldest nucleus may have been the Samara culture, at a bend in the Volga.A wider "horizon" developed, called the Kurgan culture by Marija Gimbutas in the 1950s. She included several cultures in this "Kurgan Culture", including the Samara culture and the Yamna culture, although the Yamna culture, also called "Pit Grave Culture", may more aptly be called the "nucleus" of the proto-Indo-European language. From this area, which already included various subcultures, Indo-European languages spread west, south and east starting around 4,000 BCE. These languages may have been carried by small groups of males, with patron-client systems which allowed for the inclusion of other groups into their cultural system.
Eastward emerged the Sintashta culture, where common Indo-Iranian was spoken. Out of the Sintashta culture developed the Andronovo culture, which interacted with the Bactria-Margiana culture. This interaction further shaped the Indo-Iranians, which split at sometime between 2000 and 1600 BCE into the Indo-Aryans and the Iranians. The Indo-Aryans migrated to the Levant and South Asia. According to Witzel, the spread of Indo-European languages and culture into Northern India could have been driven by small groups. Their culture and language spread by the same mechanisms of acculturalisation, and the absorption of other groups into their patron-client system.
Anthropology: elite recruitment and language shift
Indo-European languages probably spread through language shifts. Small groups can change a larger cultural area, and elite male dominance by small groups may have led to a language shift in northern India.David Anthony, in his "revised Steppe hypothesis" notes that the spread of the Indo-European languages probably did not happen through "chain-type folk migrations", but by the introduction of these languages by ritual and political elites, which were emulated by large groups of people, a process which he calls "elite recruitment".
According to Parpola, local elites joined "small but powerful groups" of Indo-European speaking migrants. These migrants had an attractive social system and good weapons, and luxury goods which marked their status and power. Joining these groups was attractive for local leaders, since it strengthened their position, and gave them additional advantages. These new members were further incorporated by matrimonial alliances.
According to Joseph Salmons, language shift is facilitated by "dislocation" of language communities, in which the elite is taken over. According to Salmons, this change is facilitated by "systematic changes in community structure", in which a local community becomes incorporated in a larger social structure.
Genetics: ancient ancestry and multiple gene flows
Genetic studies have revealed that at the start of the second millennia B.C.E., the South Asian population was significantly comprised from a mix of Ancient Ancestral South Indians, and Iranian Farmer ancestry, with a cline, running from North West to South, correlating with the admixture of Iranian Farmer ancestry. The Indus Periphery Cline, associated with the population of the Indus Valley Civilisation, had a majority of Iranian Farmer heritage, a minority of AASI, and had no detectable Steppe ancestry. Post the decline of the Indus Valley Civilisation, in the second millennia BCE, a significant amount of male Steppe ancestry appeared in to the North West of the region, to create identifiable Ancient North Indian, and Ancient South Indian clines, the ANI cline differentiated by included Steppe heritage. These two groups mixed in India between 4,200 and 1,900 years ago, after which a shift to endogamy took place, possibly by the enforcement of "social values and norms" during the Gupta Empire. Studies indicate north and south Indians share a common maternal ancestry. While studied of living South Asian populations show a disproportionate presence of ANI / Steppe ancestry within the elite Brahmin castes, historic users and keepers of Indo-Aryan texts.Moorjani et al. describe three scenarios regarding the bringing together of the two groups: migrations before the development of agriculture before 8,000–9,000 years before present ; migration of western Asian people together with the spread of agriculture, maybe up to 4,600 years BP; migrations of western Eurasians from 3,000 to 4,000 years BP.
While Reich notes that the onset of admixture coincides with the arrival of Indo-European language, according to Moorjani et al. these groups were present "unmixed" in India before the Indo-Aryan migrations. Gallego Romero et al. propose that the ANI component came from Iran and the Middle East, less than 10,000 years ago, while according to Lazaridis et al. ANI is a mix of "early farmers of western Iran" and "people of the Bronze Age Eurasian steppe". Several studies also show traces of later influxes of maternal genetic material and of paternal genetic material related to ANI and possibly the Indo-Europeans.
Others have analysed the hereditary distribution of lactose intolerance, and specifically the presence of the -13910T lactase persistence mutation, found in Europe and Central Asia, across South Asia.
In parallel the dating, and genetic lineage, of the domestic horse within South Asia is a field of research.