You can read the full treatment here, but thanks to Zack Ajmal we now know with a high degree of certainty aspects of chronology in regards to the peopling of South Asia. If you are brown you know that particular linguistic terms are used to represent ancient population movements. There has long been some dispute over whether the Austro-Asiatic Mundari people are India’s original autochthons, or if the Dravidian tribal populations are. The concept of a autochthonous group whose cultural legacy remains down to the present may itself be an illusion, but we can assert one thing: the Mundari are relatively recently newcomers to South Asia, and intrusive from Eastern Asia. This was clearly established by a paper last fall. But, thanks to Zack, and to a lesser extent other genome bloggers, we can full flesh out a chronological sequence.
First, some terms:
ANI = “Ancestral North Indian,” a West Eurasian population related to those of the Middle East and Europe
ASI = “Ancestral South Inidan,” a South Eurasian population more closely related to East Eurasians than West Eurasians, but distant from both
ANI2 = “Ancestral North Indian 2.” I will use this term to refer to those West Eurasian groups which are distinct from ANI. In Zack’s run he labels them Middle Eastern and European, but basically it describes the full range of genetic variation of West Eurasia whicn can not be extracted from the one dominant in South Asia
SEA = Southeast Asian. This is a catchall for Southeast Asian and South Chinese groups
NEA = Northeast Asian. This is a catchall for Northeast Asian and Siberian groups
Here are a set of South Asian populations as a combination of these categories in rank order of weight:
Punjabis, Pakistanis = ANI > ASI > ANI2
South Indian tribals = ASI > ANI
Mundari tribals = ASI > ANI > SEA
Khasis = SEA > ANI ~ ASI > NEA > ANI2
Non-Dalits/Non-tribals in most of India = ANI ~ ASI
Iranians = ANI2 > ANI
Southeast Asians = SEA > EA > ASI
What is this telling us? Because of genetic data we know that the common ancestor of Mundari and other East Asians has to be within the last 10,000 years. We also know that the Khasi exhibit a stronger affinity to East Asians, and, they have a residual which connects them to Tibeto-Burman populations. Interestingly, the non-East Asian ancestry in the Mundari is ANI and ASI, but not ANI2. ANI2 seems absent in most Dravidian populations excluding Brahmins.
I believe from this we can conclude that the ANI + ASI synthesis which serves as the base for almost all South Asians predates the arrival of the Mundari. They are not the original autochthons. Their distinctive genetics also does not exist outside of the northeastern quadrant of the subcontinent, suggesting that their expansion was limited to the regions suitable for their agricultural toolkit. The Khasis came later, and admixed with the substrate around them, which by that period did have ANI2. In the rest of India ANI2 seems correlated with a second wave of West Eurasians which arrived after the ANI + ASI synthesis of yore, but, the lack of this element among Mundari tribals indicates to me that they postdate these groups. Most of the Munda populations were probably Indo-Aryanized and served as some of the base for the peasantry of eastern India. These groups, which also received some ANI2, then further admixed with the second Austro-Asiatic pulse, as well as Tibeto-Burmans. The lack of ANI2 in the modern Mundari is a function of the self-selection of these groups which isolated themselves and opted out of the cultural system of the lowlands.