Native Americans survived the dangers of life except smallpox

Native Americans for thousands of years survived the dangers of life in the wilderness — inter-tribal warfare, wild animals, extreme weather, starvation, and the white man.

But just as deadly were white man diseases — especially smallpox, against which they had no natural immunity.

In the West, from 1780 through 1782, smallpox (Variola Major) took the lives of up to half the Shoshones, also decimating the Blackfeet, Sioux, Cheyenne, Mandan, Assiniboine and others. Tribes along the Pacific Coast from Alaska to California were also hard hit. So many tribes were reduced in size because of the disease, they were unable to effectively stop the invasion of whites into their ancestral lands.

http://www.cdapress.com/columns/syd_albright/article_0c88cb5c-b047-11e5-be73-10604b9f0f84.html