Villages range in size from about SO to 300 persons. Compared to the households of the other groups Yao households are the largest, averaging 7.3 persons. Yao households in Tak, Phayao, and Lampang provinces are even larger, with an average of 10.4, 8.3, and 8.0 persons respectively. In the past, Yao lived in large villages supported by abundant primary forest land. Later, when the land was exhausted, they split the villages and formed smaller ones. The average village has twenty-one houses, fewer than among the Karen, Akha, Lahu, Lisu, and Miao. The traditional Yao house is of the rectangular type and uses the ground as the floor. The house is made of bamboo (only some parts, such as the poles, are made of solid wood) and has cylindrica- thatch roofing. Houses are arranged in a line facing the lower part of the mountain. Water is brought from the mountain slopes to the village via bamboo tubes. Since Yao are Thai citizens and it is now difficult to move as freely as they did in the past, they tend to settle permanently and construct their houses off the ground, with planked floors and tile or galvanized iron roofs.