According to some historians, the Khmu were the first people to settle in today’s Oudomxay Province around the year 700. In about 1260, ethnic Lai migrated from Sipsongpanna in southern China, and built Ban Luang Cheng (Big Village) in the area of today’s Muang Xay. This original Lao Lai village remains part of Muang Xay and is called Bang Cheng.
Lai culture, which followed Buddhism mixed with Khmu traditions, grew and became regionally influential. The Khmu and resident Tai Lue lived together and shared the same rice fields. For protection, they erected fortifications between the villages of Na Sao and Na Lai. In 1828, Hmong tribes from China began to settle in Oudomxay.
Oudomxay was a part of Luang Prabang until 1961, when it was declared Souvanhnaphoum Province. The name was changed to Muang Xay Province in 1965, before finally being declared Oudomxay in 1969. In 1987 the provincial capital moved from Ban Nahin to Muang Xay, and in 1992, the districts of Pak Tha and Pha Oudom were reassigned to Bokeo Province.
Sources: Lao Ministry of Information, Culture, and Tourism
Levinson, David; Christensen, Karen (2002). Encyclopedia of Modern Asia.