The traditional Missouri River bottomland home of the Three Affiliated Tribes for a millennium, Fort Berthold Reservation is now composed of four sectors in four counties (McLean, McKenzie, Mountrail, and Dunn) separated by the Lake Sakakawea reservoir and Garrison Dam (ML4). Comprising Mandan, Hidatsa, and Arikara nations, these tribes traditionally farmed corn, beans, squash, and sunflowers. Tribal members typically lived in semipermanent earthlodges. The Mandan people were nearly wiped out by the smallpox epidemic of 1786. Only about 1,250 Mandan people remained at the time Lewis and Clark’s Corps of Discovery arrived in 1804. Smallpox again devastated the Mandan population from 1837 to 1840. The Hidatsa population was estimated by the Lewis and Clark expedition to be about 2,600. Estimates put the population at about 30,000 before smallpox arrived twenty years earlier. The three tribes united in 1862 in Like-a-Fishhook Village on the Missouri River. Since 1870 many influential tribal elders have lived on Fort Berthold Reservation, and there are currently 10,400 tribal members.