The Co lao have a population of about 1,500 persons, living in Dong Van and Hoang Su Phi districts (Ha Giang province). They are also called Ke lao. The Co lao language belongs to the Kadai Group.
In Dong Van, the Co lao practice terraced fields and grow maize in mountain rock hollows. In Hoang Su Phi they grow rice in submerged fields or in hilly soil. Basketry and woodwork are their popular handicrafts producing bamboo mats, lattices, large winnowing baskets, panniers, tables, chairs and horse saddles.
Co lao males wear trousers like many other ethnics in the northern borderline. Co lao women wear trousers and a five-panel dress running below the knees, buttoning under the left armpit, and decorated with bands of cloth of different colors attached to the chest from the middle to the right armpit along the fringe slit.
Each village has about 15-20 households. Their houses are built level with the ground, commonly with three bays and two lean-tos. Each house is a small family comprising parents and children; married sons rarely live with parents.
Each Co lao group has a definite number of family lineages. The matrilineal pattern is adopted. According to customs, a son of a paternal aunt can marry a daughter of a maternal uncle. Co lao women at child-bearing observe strict abstinence to facilitate delivery and give healthy babies.
In Dong Van, people incinerate the placentas of new-born babies then put them into rock holes in the forest so that they are not trampled upon by dogs or pigs. Three days and nights (for sons) and 2 days and 3 nights (for daughters) after birth, the babies are baptized by their parents. The first child receives the name given by its maternal grandmother. The dead person is buried with the fasting rite. At burial, rocks are placed in circles around the tomb; each circle corresponds to 10 years of age of the dead; the rock circles are then covered with earth.
Ancestors of 3-4 generations are allowed to be worshipped at home; the genie of the earth is venerated by each family and the whole village; the genie of the terraced fields is represented by a queer stone placed in the highest rock hole. Ceremonies and festivals are held on the 3rd of the 3rd lunar month, the 5th of the 5th month, the l5th of the 7th month, the 9th of the 9th month, etc. and the New Year Festival is the biggest.