How did Tibeto-Burman peoples spread across East and Southeast Asia?

The Tibeto-Burman peoples originated from a Proto-Sino-Tibetan homeland, likely located on the Plateau of Tibet near the headwaters of major rivers such as the Yangtze, Mekong, and Brahmaputra.1

From this region, these populations slowly fanned outward along these river valleys. Their dispersal was further influenced by the southward expansion of Chinese civilization and Chinese-speaking populations, which began during the Zhou dynasty and intensified through the Qin and Han dynasties. As this expansion occurred, the original inhabitants of southern China—including Tibeto-Burman, Tai, and Hmong-Mien groups—either merged with the Chinese population or migrated southward into mainland Southeast Asia and various upland enclaves.12

While these movements began much earlier, Tibeto-Burman speakers did not penetrate deeply into peninsular Southeast Asia until the middle of the 1st millennium CE, where they encountered established Austronesian and Mon-Khmer populations.1