Name of Ethnic Group: Tay (Tho, Ngan, Phen, Thu Lao, and Pa Di).
Population: About 1,200,000 people.
Locality: The Tay live along the valleys and the lower slopes of the mountains in Cao Bang, Lang Son, Bac Thai, and Quang Ninh Provinces, and in some regions of Ha Bac Province.
Customs and Habits: Ancestor worship is a religious rite of the Tay. The altar for the ancestors are placed in a central location in the house. The altar room is such a sacred place that guests are not allowed to sit on the bed in front of the altar. After giving birth,  women are also not allowed to sit on the bed in front of the altar.
Tay villages are always built at the foot of a mountain and is often named after a mountain, field, or river. Each village contains about 15-20 households.
Culture: The Tay language belongs to Tay-Thai Group. There is a rich traditional folklore with all kinds of poems, songs, dances, and music. Tay songs include the "Hat Luon" (a kind of duet between lovers), wedding songs, and lullabies.
Costumes: Tay women wear knee-length dresses, which are split at the right side with five buttons along the armpit, and a narrow sleeves.
Economy: The Tay have developed agricultural practices quite well and are able to cultivate all kinds of plants including rice, maize, and sweet potato.
THAI
Name of Ethnic Group: Thai (Tay, Tay Dam, Tay Khao, Tay Muoi, Tay Thanh, Hang Tong, and Pu Thay).
Population: More than 1,000,000 people.
Locality: Lai Chau, Son La, Hoa Binh, and Nghe An Provinces.
Customs and Habits: The Thai worship their ancestors, the heavens, the earth, ban, and "muong". They also hold rituals to pray for good crops.The Thai live in houses built on stilts. Among the Black Thai, they prefer roofs that are shaped like a tortoise carapace with decorations called "khau cuts" at each ridge. A Thai man first lives with his wife's family for several years until the couple has a child; they then move to the house of the husband's family. The Thai organize funerals as a farewell party to see off the dead to the other world.
Culture: The Thai language belongs to the Tay-Thai Group. They have a valuable legacy of myths, legends, ancient tales, versed stories, and folksongs. They like to sing and recite the "khap" along with the accompaniment of string instruments and a dance performance. Their folk dances such as "Xoe", "Sap", "Han Khuong", and "Con" are reflection of the Thai's unique cultural characteristics.
Costumes: The men have adopted the Kinh's clothing style, while Thai women have retained their traditional clothes which includes short vests, long black skirts, scarves, and ornaments.
Economy: The Thai are experienced in cultivating rice and orchards. They also breed cattle and poultry, make bamboo articles, weave cloth, and produce ceramic ware.