After Americans won the war with Mexico in the 1840s, Americans began encroaching on land that Indians of the southwest regarded as theirs. This territory was not to be given or transferred to the United States without their permission. The Indian nations in the western United States came under siege by Americas doctrine and belief of Manifest Destiny, and their God-given right to occupy all lands west to the Pacific Ocean, but were almost completely wiped out by disease, emigrants looking for land, and gold. .
In California, after the discovery of gold in1848 native Indian populations of northern California began to disappear by the massive upheavals that followed. When the Spaniards first came to the area many years before the local native populations thrived. They numbered as many as 300,000 in that region of the country, but by the time of the gold rush they numbered a mere 30,000. This was due to disease, starvation, enslavement, and murder, all this happened by 1861.
The Americans depicted the Indians as degenerate and primitive, no better than wild animals. This resulted with miners, settlers, and volunteer companies to organize and hunt down Native Americans in systematic campaigns of extermination to all that stood in the way of their progress objectives, and goals. A well-known example of this would happen in northern California near Clear Lake, when members of the Pomo tribe murdered two aggressive and greedy miners that had ruthlessly exploited their Indian laborer. This resulted in American soldiers in 1850, killing more than 100 Pomo Indian men, women, and children.
Thousands of native women and children throughout California were forced or sold into slavery, poverty and starvation forced many women into prostitution. This was the result of the large influx of single men. That came to work in the gold fields, and put these women in a precarious often-perilous situation.