The California region is bordered by the Sierra Mountains to the east and the Pacific Ocean to the west. The heart of the region sits between two mountain ranges and is fed by life giving waters from the San Joaquin and Sacramento Rivers. Rainfall decreases from north to south. During the winter, the north receives a large amount of precipitation which sustains tall forests. Further south, the region becomes drier and drier and finally gives way to the very dry landscape of the Mojave Desert.
The California region offered plenty of wild plants and game, so the first people to arrive in the region prospered without the need for agriculture. They built highly populated permanent villages. Their dietary staple was flour ground from acorn kernels gathered from oak trees. The also sundried wild plants, berries, roots, and seeds for later use in cake making. The inhabitants of the California region were effective game hunters using snares and traps to catch small game, and bows, arrows and clubs for larger prey. They were also accomplished inland and coastal fisherman who used hooks, lines, nets, spears and weirs to catch fish. In coastal tidal basins, they also gathered other ocean food like oysters, mussels and abalone.
House construction in the California region varied, but the predominate shape was conical. The building materials were mainly wooden poles, brush and grass reeds. In the northern part of the California region, houses were constructed from wooden planks with building techniques similar to those of the Northwest Coast. Most houses were single-family dwellings, but larger structures were built for communal and ceremonial purposes.
As many as a hundred different dialects can be found in the California region. These languages are generally divided into four groups:
- the Athapascan language family, spoken by northern peoples like the Hupa;
- the Hokan family phylum, spoken by the are Chumash, Pomo and Yahi peoples;
- Penutian language family, spoken by the Miwok, Wintun, and Yokuts peoples;
- the Uto-Aztecan language family, spoken by the southern groups who became known as the Mission Indians.