If you have not read my post “To the antipode of Asia”, this might be a good time to do so if you are unfamiliar with the history, prehistory, and ethnography of mainland Southeast Asia. In this post I will focus on mainland Southeast Asia, and how it relates implicitly to India and China genetically, and what inferences we can make about demography and history. Though I will touch upon the Malay peninsula in the preliminary results, I have removed the Indonesian and Philippine samples from the data set in totality. This means that in this post I will not touch upon spread of the Austronesians.
I present before you two tentative questions:
- What was the relationship of the spread of Indic culture to Indic genes in mainland Southeast Asia before 1000 A.D.?
- What was the relationship of the spread of Tai culture to Tai genes in mainland Southeast Asia after 1000 A.D.?
The two maps above show the distribution of Austro-Asiatic and Tai languages in mainland Southeast Asia. Observe that when you join the two together in a union they cover much of the eastern 2/3 of mainland Southeast Asia. The fragmented nature of Austro-Asiatic languages in the northern region, edging into the People’s Republic of China, implies to us immediately that it is likely that in the past there was a continuous zone of Austro-Asiatic speech in this region. From the histories and mythologies of the Tai people we know that this group migrated from the southern fringes of China around ~1000 A.D. This is obvious when we note that there are still Tai people in southern China, and the expansion of the Tai across what is today Thailand is to some extent historically attested. Between 1000 and 1500 there was a wholesale ethnic reorganization of the Chao Phray river basin. Was that a matter of demographic replacement, or cultural assimilation, or some of both?
Second, what was the impact of Indians upon mainland Southeast Asia? One of the easiest ways to ascertain Indian influence is script. Burmese, Thai and Cambodian scripts all derive from Grantha, an archaic Tamil script (non-Islamic scripts in island Southeast Asia, such as Javanese and Balinese, are also derive from South Indian precursors). The Indian religious influences also are more southern than northern, manifesting in the southern forms of Shaivite Hinduism and Sri Lankan Theravada Buddhism.
As I am currently reading Victor Lieberman’s magisterial Strange Parallels: Volume 2. So I was very interested in a new paper from BMC Genetics, Genetic structure of the Mon-Khmer speaking groups and their affinity to the neighbouring Tai populations in Northern Thailand, pointed to by Dienekes today. Here are the results and conclusions:
A large fraction of genetic variation is observed within populations (about 80% and 90 % for mtDNA and the Y-chromosome, respectively). The genetic divergence between populations is much higher in Mon-Khmer than in Tai speaking groups, especially at the paternally inherited markers. The two major linguistic groups are genetically distinct, but only for a marginal fraction (1 to 2 %) of the total genetic variation. Genetic distances between populations correlate with their linguistic differences, whereas the geographic distance does not explain the genetic divergence pattern.
The Mon-Khmer speaking populations in northern Thailand exhibited the genetic divergence among each other and also when compared to Tai speaking peoples. The different drift effects and the post-marital residence patterns between the two linguistic groups are the explanation for a small but significant fraction of the genetic variation pattern within and between them.
There are many occasions when it has taken a synthetic scholar to point out to me the overall structure of a constellation of facts which I was conscious of prior. So it is with Lieberman’s work. I had known that the eruption of the Thai peoples into Southeast Asia occurred with the last 1,000 years, before which the peninsula was divided between Tibeto-Burman populations to the west and Austro-Asiatic languages to the east (the latter divided between the Khmer and Vietnamese). Additionally, it is presumed that the Tibeto-Burman languages themselves displaced Austro-Asiatic in the western zone (as evident by the persistence of Mon in modern Burma). What was noted in volume 1 of Strange Parallels though is that the three geographical regions engaged with and assimilated the Thai invasions different. In the center the Thai succeeded in dominating the previous groups and imposing their identity upon the region. It is often asserted that modern Cambodia’s existence as an independent state is a function of the protection conferred upon it by the French from the expansive ambitions of the Empire of Siam. But in the east the Vietnamese state was barely impacted by the Thai folk wandering. As in China the Thai in Vietnam are marginalized “mountain tribes.” Finally, in the west, in the zone which became Burma, the Thai did not take over the cultural commanding heights. But neither were they absolutely marginalized as in the east. Rather, the Shan people became part of the of the Burmese landscape, integrated into the Theravada Buddhist culture, but also a significant secondary ethnos to the Burman majority (along with Karens, Mons, etc.).
What does this have to do with genetics? Possibly everything and nothing, and all answers in between.