Don Cossacks refers to Cossacks who settled along the lower and middle Don River, Russia. This population was formed in the second half of the 16th century largely by runaway peasants. By the end of the century they were granted certain privileges in exchange for frontier military service as Don Cossack Voisko. Since 1786 the territory was officially called Don Voisko Lands, and was renamed into Don Voisko Province (Область Войска Донского) in 1870.