Below are some sources for those of you looking for those elusive "hard facts" with which to discuss California Indian history. I've followed this up by some photos I've found online. I'll post the sources when I can.
Video clip describes the circustances in California during the1800s which legalized slavery of Native Americans. Written and produced by Doug Harris:
California Indian Timeline on a website which serves as a memorial for Indians who died as the result of Missionization and the Gold Rush: http://www.csus.edu/indiv/t/tumminia/MEMORIAL.HTM
Discussion of California Indian Slavery: http://www.jeffnet.org/~mlenk/karuk/overview_of_calif_indian_history.htm
PBS show and website about "California Genocide":http://www.pbs.org/indiancountry/history/calif.html