Patwin, or Patween, is a term that has been used to describe a large group of Native Americans who share historic similarities in language and cultural development. It is important to note that this modern usage of the term was first applied by anthropologists to organize local tribes into groups by cultural similarities, and that although Native American groups also used the term, it simply meant "people" and originally lacked any connotation of such an organizational scheme. In its academic meaning, Patwin refers to the indigenous tribes who lived in a part of the lower Sacramento Valley west of the Sacramento River and north of Suisun Bay. Three broad dialects of their common root language have been identified, and anthropologist Alfred Kroeber proposed a geo-political organization of three groups based partially on these dialects. Pooewin is the term that has been used for the dialect used by the Native Americans of the Yolo Basin. Kroeber called the people who spoke this dialect the Southern River Patwin. The Native Americans of the region organized themselves in tribelets, which were usually made up of a primary village surrounded by smaller satellite villages. The tribelet that lived along the Putah Creek, in the area around where UC Davis stands now, was Puttoy (aka Puta-toi or Putoy).
The Patwin language is part of an even larger group known as the Wintuan family which is believed to have shared a common language thousands of years ago.