Exterminate Them: Written Accounts of the Murder, Rape, and Enslavement of Native Americans during the California Gold Rush

This isn't true. The Spanish focus was on conversion, Americans on extermination. California saw a lot of brutality because manifest destiny had built up its full momentum by then, because of the discovery of gold, and because it had a high native population density for the time period, even after the Spanish mission system had done its damage. Here are a couple books on the topic:https://www.amazon.com/Murder-State-Californias-American-1846-1873/dp/0803269668https://www.amazon.com/Exterminate-Them-Enslavement-Americans-California-ebook/dp/B00CWIEEBO The title of the second book is taken from newspaper headlines.