Meanwhile, James Chamberlain claims that "Jiao" originated as a cognate of Lao. Chamberlain, like Joachim Schlesinger, claim that the Vietnamese language was not originally based in the area of the Red River in what is now northern Vietnam. According to them, the Red River Delta region was originally inhabited by Tai-speakers or other Kra-Dai speakers such as Li people. They claim that the area become Vietnamese-speaking only between the seventh and ninth centuries AD, or even as late as the tenth century, as a result of immigration from the south, i.e., modern central Vietnam. According to Han-Tang records, east of Jiaozhi and the coast of Kwangdong, Kwangsi was heavily populated by ethnic Li people (whom Chinese contemporaries called "Lǐ" 俚 and "Lǎo" 獠). Even so, Michael Churchman acknowledged that "The absence of records of large-scale population shifts indicates that there was a fairly stable group of people in Jiaozhi throughout the Han–Tang period who spoke Austroasiatic languages ancestral to modern Vietnamese."