The history of California stands in great contrast to the history of the USA's Eastern lands. There was some Spanish Mission activity dating back for several hundred years, but Native Americans representing hundreds of different tribes and several language groups dominated the California scene until about 1849 when the Gold Rush to California's Gold Country near Sacramento changed California's future quickly and dramatically.
Few California miners ever struck it rich or even stayed in the West, but the huge influx of miners along with businesses to serve the mining communities turned forts into towns and towns into larger cities. Soon, California was a key destination for American's westward migration.
California's Gold Country
The California Kids Guide has some good California history links.