Mandan burial ground, by Karl Bodmer (Library of Congress)
The small pox virus
that arrived at the Mandan Villages (most likely brought by
Comanche traders) in the summer of 1781 was especially
virulent. The thriving tribal culture of 15,000 people was
reduced to half that number within weeks. Devastated and
frightened, the survivors elected to move upstream, to the Knife
River, and join their friends the Hidtasa. Some of the
Mandans moved into Hidatsa villages through intermarriage, and
others helped to build new villages in close proximity. It
was here, twenty-three years later, that Lewis and Clark met them
for the first time.