California's Indian Population

"For over a quarter-century, Madley shows how the region became a quilt of many killing fields. Of the estimated 80 percent decline in the California Indian population during these years, around 40 percent has been attributed to outright "extermination killings" alone.":

http://www.nybooks.com/articles/2016/11/24/indians-slaves-and-mass-murder-the-hidden-history/