Sentence:  The <WSD>Tais</WSD> first appeared in history in Yunnan, and from thence they migrated into Upper Burma. The earliest swarms appear to have entered that tract about two thousand years ago, and were small in number. 
Meaning of the word marked with <WSD> tags:  A descendant of speakers of a common proto-Tai language, including subpopulations which no longer speak a Tai language.