Particulary I'm interested in Southern California but a broader geographical range would be acceptable.
Also any other suggestion for other periods of California history if there are any gems you know.
You might look at Heyday Books for histories and collections of lore dating back to pre-contact times.
California history before contact is prehistory. So here are some prehistory, ethnohistory/ethnology and early history resources.
Try California Archaeology, Michael J. Moratto, 2004. Second Edition, Coyote Press, Salinas. Originally published in 1928 as a Bureau of American Ethnology Bulletin, Kroeber's work is timeless and invaluable.
also Handbook of California Indians, Alfred Kroeber, 1976, Dover Publications, New York
and Handbook of North American Indians, Volume 8 California, 1978. Robert Heizer vol. editor. Smithsonian Institution, Washington