 Contact with Europeans and the frequent interaction between tribes accelerated the several epidemics that swept the region, beginning with smallpox in the 1770s and continuing with what was likely malaria in 1829, cholera in 1836, and smallpox again in 1853.The native population dropped from thousands to a few dozen.So many Chinooks died around Willapa Bay in the 1850s that the Chehalis moved in to take their place.