It is believed that Paipai was separated from the Northern Pai languages many years ago. In oral tradition of most Yuman tribes, the people descended from Avikwame (also known as Newberry Mt.) and went were Kumat directed them. So at one time the Paipai might have been with the other tribes.
The Paipai language was documented by Judith Joël and Mauricio J. Mixco, who have published texts and studies of syntax.
Paipai belongs to the Yuman language family. Within the Yuman family, Paipai belongs to the Pai branch, which also includes the Upland Yuman language, dialects of which are spoken by the Yavapai, Walapai, and Havasupai of western Arizona. The relationship between Paipai and Upland Yuman is very close; some observers have suggested that Paipai and Yavapai are mutually intelligible (i.e., that the Paipai and Upland Yumans spoke dialects of a single language), while other observers have claimed that they are not.
The controversial technique of glottochronology suggests that the Pai branch of Yuman may have separated from the other two branches of Core Yuman (River Yuman and Delta–California Yuman) about 1,000-1,700 years ago. Paipai may have separated from Upland Yuman 1,000 years ago or less.