Genetic footprint of Sino-Tibetans along the Southwest Silkroad

The Chinese civilization developed as an amalgamation of various strings of technologically advanced neolithic, and early bronze age cultures transmitted through two main routes: the northern route and the southern route. The northern route connects west Eurasia and Central Asia to China proper in the Yellow River basin through the upper Yellow River corridor (the Hexi corridor), which traverses across modern Gansu and Xinjiang. The northern route may also encompass the Mongolian plateau where the sites of Afanasevo bronze culture were found, and whose far eastern extension manifested as early bronze age Qijia culture in Ganzu. The less discussed southern route, on the other hand, consists of a land branch and a maritime branch. The maritime route connects southeast Asia with coastal eastern China and populated the latter region by the proto-Austrasiatic, Kra-Daic, and Hmong-Mien people. The land route connects southwestern China (Yunnan and Sichuan) and the Tibetan Plateau to Burma, northeastern India and modern Bangladesh, and ultimately taps with the Semitic and Indo-European cultures in western Eurasia. The southern route later became known as the Southwest Silkroad, and the northern route was developed into the Northwest Silkroad. Most subsistence products (animals and plants), metallurgy and pottery techniques, linguistic origins, transportation and weaponry, which used to be thought as indigenously developed, are now found to have been imported or directed implanted from civilizations along these two main routes.

The northern route was relatively well studied by archaeologists and historians dated back to the early 20th century. For example, the hallmark of neolithic culture within the scope of China proper — Yangshao culture — was the agricultural domestication of millet (both foxtail and broomcorn millet species) around 6000 BP (before present). Yet, millet was first cultivated by people outside the traditional sphere of China proper in Bohai and West Liao River regions further back in 9000-8000 BP, who is attributed to be the ancestors of a series of Trans-Eurasian languages, including Koreanic, Japonic, Tungustic, Mongolic, and Altaic languages and whose paternal Y-haplogroup had a concentration of C and C-subclades. Millet cultivation was only discontinuously spreading to Yellow River (YR) basins in the next two millenniums, being slowly adopted by the local inhabitants of YR and brought to YR basins by Trans-Eurasian people from the West Liao River. Another considerably powerful evidence undermining the demic hypothesis of a Sino-Tibetan (ST) language is the lack of etymological cognates for the staple agricultural products, millet and pig, across Sino-Tibetan languages. These different types of evidence now suggest that millet cultivation that marked the neolithic Yangshao culture, the “dawn light” of Chinese civilization with the first settled agriculture, was likely an import from West Liao River Trans-Eurasian cultures that transmitted to YR regions after the split off of Old Chinese from the Proto-ST language.

In the northern route, the earliest bronze age site ever excavated is seated in the eastern end of the route connecting upper-middle YR to Central Asia. This bronze age culture became known as Qijia culture, which is a non-indigenous bronze culture extending the Afanasevo culture found in Inner Asia and southern Siberia. Studies by Hosner et al showed a decline of archaeological sites based on millet and pig agriculture in YR region during the 2nd millennium BCE was accompanied by the introduction and growth of products and technologies originated from West Eurasia, including sheep, goat, cattle, horse, chariots, wheels, wheat, and barley. The first archaeologically confirmed state of China — Shang dynasty —was long suspected to have originated from Manchuria in the northeast by historian Fu Sinian. The overwhelming military advantage enjoyed by Shang people is documented as their horse-driven chariots unseen by the contemporaneous foot soldiers in the YR basin. This exact chariot technology and horse domestication, along with sheep and cattle, was transmitted via the northern route by agro-pastoralists from Central Asia and the western Eurasian steppe, by a branch of the Indo-European people whose expansion took place in the 3rd–2nd Millenium BCE and reached YR China proper by the end of 2nd Millenium BCE ().

The southern route of the grand cultural connection between China and western Eurasia, namely the Southwest Silkroad, consisted of a maritime and an inland trail. The connection occurred between China and northeastern India and modern Bangladesh took place along the land route, which will be the focal discussion of the current chapter. The maritime route spread the population belonging to Y-haplogroups O-M95 and O-M119 along southeast Asia and coastal China, from modern-day Guangzhou to as far north as Shandong. Haplogroup O-M95 overlapped and concentrated among the speakers of Austrasiatic languages, incluidng Munda, Khmer, and Vietnamese, as well as southern Han Chinese; whereas O-M119 is often found among Austronesian and Kra-Daic speakers in addition to southern and eastern Han Chinese. These demographic groups correspond closely to Hundred Yue/Viet (百越) and Hundred Pu/Pyu (百濮) barbarians recorded in Chinese historical writings including Shiji and Han Book. Even today, the endonyms of southeastern Han Chinese cultures still retain the vestige of this ancient connection to Austroasiatic and Austronesian civilizations by having the word “Yue/Viet” in titular appellations, such as Wu Yue (Ngoyue), Min Yue (Menve), and Nan Yue (Namyuet). The festival activity of dragon canoe racing and flower boat tour, unseen in China proper, reflects the intimate cultural relevance of southeastern China to that of southeastern Asia.

Our focal interest here — the inland route of Southwest Silkroad — is of paramount importance to the peopling of East Asia because this is where major eastern Eurasia Y-haplogroups had evolved and split into modern genetic and linguistic groups since the out-of-Africa movement of homo sapiens. Ancient haplogroup D hailed from the Horn of Africa into the Arabian Peninsula, where it diverged from haplogroup M and took the maritime coastal route to Andamese Island and, northward, to Bangladesh. Around 60 kya, bearers of descendant haplogroup D1 and D3 traveled further north to Yunnan and across the Himalayas to Tibetan Plateau. Today, approximately 20–40% of Tibetans, 20–30% of Yi, and 10–20% of Qiangic people, belong to haplogroup D (). This haplogroup is also found in some Han Chinese at a lower frequency. The relative heavier concentration of haplogroup D in these Tibetan-Burman groups suggests that, first, the Tibetan-Burman branch of the Sino-Tibetan language family received a distinct genetic foundation different from Han Chinese; second, as an earlier human migrated into modern China, haplogroup-D predates haplogroup-O, which is the foundational haplogroup in most Chinese ethnic groups including Han Chinese. Travelling further north, haplogroup-D is found among modern-day Mongolians, Koreans, and various Turkic groups in Xinjiang. The migratory map of haplogroup-D depicted that northeastern India and Bangladesh were the main watersheds that formed the initial peopling of China.

Twenty thousand years later, around 40 kya, ancient haplogroup-NO followed the steps of haplogroup-D to arrive in the vicinity of northeastern India and Bangladesh. Haplogroup-O is the major genetic lineage found in East Asia and is particularly prevalent in populations from China, Korea, and Japan. After diverging from its antecedent NO group and splitting from haplogroup-N around 20–10 kya, haplogroup O began to expand and diversify within East Asia around 25,000 to 20,000 years ago. This coincided with the retreat of the glaciers and the subsequent reoccupation of the region. The migration routes and patterns of this expansion are still being studied, but it is believed that Haplogroup O mainly spread across East Asia by 1) traversing eastward to southeast Asia and then into southern China, where O-M95, O-M119 and O-M7 groups were developed, and 2) northward route into modern Sichuan and Yunnan, before it finally reached upper and middle Yellow River and evolved into one major ancestral lineage of modern Han Chinese — O-M134*117 as well as other Sino-Tibetan groups. Another study (Shi H et al 2005) showed that most of the major STR haplotypes occurred in southern populations living in modern-day Burma, Yunnan, Thailand, and northeastern India, which is likely the origin place of haplogroup-O.

The intriguing evolution history of haplogroup-O reveals that this ancestral group probably stayed longer in the vicinity north to Bangladesh and in southeast Asia before it diverged into different mutation groups. Analysis of haplotypes based on short tandem repeat (STR) indicates that O-M7 (mainly Hmong-Mien people) and O-M95 (mainly Austro-Asiatic people) were closer to undifferentiated O* before the evolution bottlenecks imposed by climate and topography were broken off by proto-Sino-Tibetan ancestors who were marked by O-M122 (Cai, X et al 2011). This means that the ancestors of Sino-Tibetan people stayed in the warmer woodlands of Asia in 20–25 kya and departed at this point to venture northward into the semi-arid scrubs of modern-day Yunnan en mass. The northward migration of O-M122 initiated around northeastern India and Burma around 20 kya, they traveled up to the Salween River or Mekong River into Yunnan. Through the Zomia highlands and forests, they moved into Sichuan and eastern Tibetan Plateau, a region that then became the homeland of the proto-Sino-Tibetan language (van Driem, 1999). The estimated time of the arrival of the ancestral Sino-Tibetan people into China varies by studies, but a general consensus is 25 kya, about 18–20 thousand years ahead of the Yangshao neolithic culture, which ushered in ancient Chinese civilizations (Cai, X et al 2011; Shi H et al 2005). Before their long march to China, both O-M122 and O-M95 had left genetic footprints in Bangladesh and northeastern India. Today, a large number of Austro-Asiatic people live in Bangladesh (Munda and Khasi), and several Tibetan-Burman nationalities claim northeastern India and Bangladesh as their traditional homeland (e.g. Meithei, Mizo, Garo), although the Tibetan-Burman groups in South Asia are likely later migrants from Tibet and Yunnan.

Many Chinese people today also carry haplogroup-C, which is found concentrated among Mongolic and Tungustic people in northern Tran-eurasian forests and steppes from Korea to Altai Mountain. Haplogroup-C is believed to have taken the maritime route of coastal southeast Asia and eastern China before reaching the West Liao River and spreading to Trans-Eurasia, thus it has left genetic footprint all over eastern China, Korea, Manchuria, and the Mongolian Plateau. Both Ghengis Khan and Confucius prove to share the paternal lineage of haplogroup-C2b (Wu, Q et al, 2020), confirming Fu Sinian’s hypothesis of the Manchurian origin of Shang Dynasty. However, the maritime transmission route of haplogroup-C had less to do with northeastern India and Bangladesh, we will leave it out of the scope of this chapter. Nevertheless, Bangladesh and northeastern India are of crucial importance in the evolutionary history of human genetics because this region is the only gate for out-of-Africa homo sapiens to go into East Asia during the Last Glacial Maximum around 20 kya. The northwestern Silkroad was closed off by extreme coldness, and the Himalayas were naturally inhibiting. Human migration into East Asia had to traverse through modern-day Bangladesh into Southeast Asia, where they flourished and developed new haplogroups including O, C, D, N, F (Hallast et al, 2020).

The genetic evolution map of haplogroups clearly carved northeast India and the Southwest Silkroad to be the most critical route for the development of any subsequent Sino-Tibetan populations, including the earliest known Chinese state that spoke an archaic Sinitic language — the Zhou dynasty (Shang, on the other hand, originated from Manchuria or Bohai-Liao River area). The prehistoric human deployment of the resources, terrains, structures of Southwest Silkroad was very antiquated and far predated the earliest written record of this route by Chinese historians. The later Sinocentric historical narrative promoted by the “tianxia” worldview, however, sees the world from a centrifugal perspective that historical importance and cultural relevance were equated with the Central Plain of China, while other regions further from the Central Plain were dismissed as barbaric. The barbarians of all four directions (the Eastern Yi, Northern Di, Western Rong, and Southern Man), in the eyes of heavily ideologized Chinese literati bureaucrats, lived in ignorance waiting for salvation by memorizing Chinese characters and kowtowing to the condescending Confucianist patriarch.

With this worldview in mind, the official narrative continuously attempts to establish how Soutwest Silkroad was a trade and civilizational project largely developed by the central government of Chinese dynasties. However, commonsense in history and economics defies such assertation. A trade route requires free flow of capital, liquidity of assets, and participating customers with diversified demands. None of these can be activated by a monopolizing agent. Quite contrarily, buzzling and booming transactional activities must already have been present among the different nationalities along the Southwest Silkroad, who each brought with their unique products and demands, before any central government can set up any profitable trade post to also benefit from trading with all other equal parties in this market.

Chinese states repeatedly tried to use the Southwest Silkroad to establish relationships with the states and tribes that resided in modern Bangladesh and ultimately with western Eurasia. The nationalist and Sinocentric ideology that dominated Han Chinese historian narratives had simply concealed the independently important roles of the Southwest Silkroad and the history of the indigenous population along this route in the making of East Asian historical trajectory. The Sinocentric narrative upholds how the central government from China proper singlehandedly created the Southwest Silkroad and enriched inland China by setting trade posts in Sichuan (Basu Commandery or Basuria) that connects to barbarian states in modern northeastern India, Bangladesh, and Burma. However, in fact, these official trade posts were short-lived and quickly abandoned due to insufficient maintenance and funding. Daily commerce had been conducting since the 2nd millennium BCE between Sichuan and western Eurasian via the Southwest Silkroad, whereas centralized Chinese attempt to establish an official trade post only first occurred in the 1st century BCE.

For example, The Record of the Grand Historian documented: when Xiongnu cut off and monopolized the Northwest Silkroad, Chinese Han dynasty’s emissary Zhang Qian found Sichuan Silk(蜀锦) and Sichuan-Tibetan Bamboo (邛竹杖) in Bactria and was surprised that indigenous people of Sichuan had been doing business with Central Asia and India via the “Sichuan-Hindu route (shu-shendu dao 蜀身毒道)” for millennia. The same book also documented that in the attempt to acquire a legendary sauce “qijiang (枸醬)” traded in Sichuan (the most southwestern territory by then), Chinese General Tang Meng tried in vain to conquer southwestern states and could not monopolize the Southwest Silkroad. The failed conquest was replaced by a peaceful mutual-cooperation strategy initiated by a Sichuan indigenous Sima Xiangru who convinced the Chinese emperor in the north that trading with them “southwestern barbarians” was not worthy of military intervention. More of a gesture to save face, the Chinese emperor Wu knew that his conquest would be defeated and the Southwest Silkroad had been firmly controlled by indigenous states long before him. The Record of the Grand Historian also recorded that Sima Xiangshu used to wear a shorts known as “bullock nose pant”(犊鼻裈) in public, a deviant and vulgar act in the eyes of Confucianists. This shorts is associated with people who “wash horse”. With archaeological evidence showing short pants were originally wore by horse herders in western Eurasia (), it is not unlikely that Sima Xiangru and other Sichuan natives had learned about wearing short pants by interacting with western Eurasian merchants via the Southwest Silkroad.