The Yao nationality (its great majority branch is also known as Mien; Pinyin: Yao zu; Vietnamese: nguoi Dao) is a government classification for various minorities in China. They form one of the 55 ethnic minority groups officially recognized by the People's Republic of China, where they reside in the mountainous terrain of the southwest and south. They also form one of the 54 ethnic groups officially recognized by Vietnam. In the last census, they numbered 2,637,421 in China, and roughly 470,000 in Vietnam. In Thailand they number 40,000 and in Laos 20,000. The Lahu are an ethnic group of Southeast Asia and China. They are of the 56 ethnic groups officially recognized by the People's Republic of China, where about 450,000 live in Yunnan province. An estimated 150,000 live in Burma. In Thailand, Lahu are one of the six main hill tribes, and their population is estimated at around 100,000. The Tai often refer to them by the exonym 'Mussur', meaning hunter. About 10,000 live in Laos. They are one of 54 ethnic groups in Vietnam, where about 1,500 live in Lai Chau province.