From the abstract

“Yunnanese are one of the Chinese sub-groups in northern Thailand who migrated overland both from Yunnan province in southwestern China and Burma. They are referred to “ho” or “chin ho” by the Thais and are differentiated from the overseas Chinese who were known as “chaek” in Thailand.”

“2) The initial stage of the formation of the Yunnanese villages is categorized into 4 types: 1) a mixture of Kuomintang soldiers and civilian Yunnanese refugees 2) villages mainly composed of Kuomintang soldiers 3) villages formed by forced migration of Kuomintang soldiers 4) villages formed by the anti-government Burmese military unit. Influenced by the socio-political and situation along the national border between Thailand and Burma, the number of new Yunnanese migrants from Burma increased after the establishment of these villages.
3) Along with the historical process of village formation, Yunnanese themselves are composed of 5 groups, i.e. 1) ex-soldiers of Kuomintang 2) civilian refugees from China 3) refugees from Burma 4) anti-government Burmese military 5) migrants for whom detailed information is not available. Among these, migration of the Yunnanese categorized as 1) and 2) started due to the China-Japanese war of the 1930s to 1940s and political turmoil in China before and after 1949. They began to settle at the border of northern Thailand from the beginning of the 1950s to the 1960s. Yunnanese categorized as 3), 4) and 5) are new migrants who began to settle in this area after the 1960s due to various reasons such as political turmoil in China, civil war and economic instability in Burma.”

http://repository.tufs.ac.jp/bitstream/10108/20202/1/jaas067007.pdf

It seems that the residency of Chinese in the mountainous continental Southeast Asia has a long history which could be traced back to the 19th or even the 18th century.