Final answer:
Native American reservations were not set up in California due to various factors, including prior displacement, the occupation of the land by European settlers, and the increasing need for land by white settlers.
Step-by-step explanation:
Native American reservations were not set up in California for several reasons. One reason is that by the time of the Civil War, most Native American tribes had already been relocated west of the Mississippi.
Additionally, the land in California was already occupied by European settlers and had become valuable for various reasons, such as rich timber resources, farms, and railway development.
The increasing population of white settlers and the need for land further marginalized Native American tribes, leading to their displacement and dependence on the Bureau of Indian Affairs for support.