The Pomo are a Native American people of California. Historical Pomo territory in Northern California was large, bordered by the Pacific Coast to the west, extending inland to Clear Lake, and mainly between Cleone and Duncans Point. One small group, the Tceefoka (aka Northeastern Pomo), lived in the vicinity of present-day Stonyford in Colusa County, separated from the core Pomo area by lands inhabited by Yuki and Wintuan speakers.

The name Pomo originally meant “those who live at red earth hole” and was once the name of a village in southern Potter Valley near the present-day community of Pomo, California in Mendocino County. It may have referred to local deposits of the red mineral magnesite, used for red beads, or to the reddish earth and clay, such as hematite, mined in the area. In the Northern Pomo dialect, -pomo or -poma was used as a suffix after the names of places, to mean a subgroup of people of the place. By 1877, the use of Pomo had been extended in English to mean the entire people known today as the Pomo.

Resource: https://en.wikipedia.org/wiki/Pomo