Houaphanh was home of the Bon Man Kingdom (Muang Phuan) beginning in the 14th century. Following a Vietnamese invasion in 1478, it became the Tran Ninh Territory of the Dại Viet Kingdom with the capital at present-day Xam Neua. The area was once known as Hua Phan Tang Ha Tang Hok, “the fifth and the sixth province.” It remained a Vietnamese outpost until 1893, when French colonial authorities switched ownership back to Laos. The province houses the Viengxay Caves, an extensive network used by the Pathet Lao during the Indochinese Wars, which are considered the home of the revolution.
Sources: Lao Ministry of Information, Culture, and Tourism