The first Cossack settlements appeared in the late fifteenth century in the region of the lower Don. Most of these people were fugitives who chose to settle along the Don, out of reach of the Russian authorities. With the increasing population along the Don in the second half of the sixteenth century, the Don Cossacks emerged as an important military and political force in the area. Dependent on Moscow economically and militarily, they nevertheless remained politically and administratively independent, residing in the borderlands of the Russian and Ottoman states. In the late seventeenth century the Russian government attempted to limit their freedom and privileges. It was the demand that fugitives be returned that Cossacks saw as the greatest violation of their traditional liberties. By the end of the eighteenth century the frontier had moved farther south and the military significance of the Don Cossacks diminished. After 1738 the Don Cossacks' chief commander, who formerly was elected, became an appointee of the Russian government, and after 1754 the local commanders also were appointed by the Ministry of War in St. Petersburg. Through this and other moves, the Cossacks were completely absorbed into the Russian military and performed military service throughout the Russian Empire; during the reign of Czar Paul, for example, they were ordered "to conquer India," and they had actually set off when, after his assassination, the insane directive was remanded. The Cossack gentry was created by the edict of 1799; Cossacks became equal in rank to the rest of the Russian military. In 1802 the lands were divided into seven districts administered by the Ministry of War; in 1887 the number of districts was increased to nine. By 1802 the Don Cossacks could furnish eighty cavalry regiments. Each enlisted Cossack had to serve thirty years. In 1875 military service was cut back to twenty years. They were particularly notorious for their role in suppressing revolutionary movements in Russia and the massacre of Jews during pogroms. During World War I the Don Cossacks formed fifty-seven cavalry regiments (i.e., nearly 100,000 horsemen). After the February Revolution of 1917 their chief commander, A. M. Kaledin, declared the formation of the "Don Cossack government." After Kaledin and his counterrevolutionary government were crushed, the "Don Soviet Republic" was promulgated in March 1918. However, the new Soviet policies of nationalization and the appropriation of surpluses led to an uprising in the Don region and elimination of the Soviet government. In January 1920 the Soviet troops returned to reestablish Soviet control of the area and to abolish any administrative autonomy in the region. The last reminders of past glory were several Don Cossack regiments formed in 1936 within the Soviet Army. During World War II these regiments proved to be hopelessly outdated cannon fodder and were eventually disbanded.
Historically the Don Cossacks bordered the Kalmyks in the east, the Nogays and the Crimean Tatars in the south, Russians in the north, and Ukrainians in the west. Today the region includes these and other ethnic groups of the USSR.