In China the Tho have been included as part of the large Zhuang nationality. In Vietnam the Tho are known as Tay. They are different from another group in Vietnam also named Tho.
In the early 1900s Presbyterian missionary J. H. Freeman surveyed the Tho language. He reported, "Tone and pronunciation are quite close to [Tai] Lu. I made a vocabulary of 400 common words, and found only 67, or one in six, which cannot readily be identified with anything in the [northern Thai] dialect. There is, however, a large admixture of Cantonese and Mandarin in their words." One recent study remarks that "speakers of southern Zhuang varieties, such as Debao call themselves Tho, but for speakers in Vietnam the term appears to be considered pejorative."
The ancestors of the Tho migrated south into Guangxi under pressure from the advancing Mongol armies in the thirteenth century. "From Guangxi a number of tribes pushed into Vietnam and Laos, such as the Tho." The Tho in northern Vietnam were the only tribe who would not submit to the rule of the Hmong king, Sioung, in the late 1800s. Sioung was outraged and led a military campaign against the Tho for 12 years. Countless villages were burned and thousands of Tho were murdered. Most Tho fled the mountains to the lowlands to get beyond the reach of the Hmong.
The Tho choose to live at the foot of a mountain or near a stream. Their homes consist of two main rooms, the front one for men and the rear one for women. The Tho possess a rich traditional folklore of poems, songs, and dances. One form of song is the luon, a duet where lovers sing romantic verses to each other.
Ancestor worship is the primary religion among the Tho in China today. An early missionary describes the external differences he saw between the Tho and Nung: "There are several factors which seemed to designate the Tho as the more strategic tribe of the two: The Tho are much finer looking; in fact they are the finest looking people we have seen among the natives of Indo-China; They cultivate their fields and gardens better, live in cleaner houses, and seem generally thriftier and more intelligent than the Nung."
There are a small number of Christians among the Tho in both China and Vietnam. Many have been exposed to the gospel through the FEBC radio broadcasts. As early as 1913 there were a reported 4,000 to 5,000 Tho Catholics in China. Missionaries translated several books of the Bible into Tho in 1938, but these have been out of print since 1963. The script used was an ancient form of sixteenth century Chinese characters; few, if any, would be able to read it today. Two Tho dictionaries exist to aid those who wish to learn their language.