The Blackfoot roamed the northern plains between the upper Missouri and Saskatchewan rivers.  They consisted of three distinct divisions:  the Siksika (Blackfoot proper), the Kainah (Bloods), and the Piegan.  Originally from Saskatchewan, in the mid-18th century, they drifted into the Montana area in search of buffalo.  By the mid-19th century (at the peak of their power), they controlled a vast territory.

The Blackfoot were expert horseback riders, noted buffalo hunters, and fierce warriors.  They were feared by other Native American groups, and were frequently at war with their neighbors the Cree, Sioux, Crow, and other tribes.  In times of war, the three divisions united to defend their lands.

The Blackfoot were a nomadic tribe, living in teepees in easily dismantled villages.  The tribes were divided into several bands, each led by a chief.  Except for growing tobacco, the Blackfoot did no farming; their culture and economy were thus essentially typical of those of the Plains tribes.  While the men made weapons and hunted, the women did household chores and gathered wild plants for food.  The Blackfoot practiced polygamy.  A prosperous warrior might have several wives.

While generally friendly to the Hudson's Bay Company traders, they were (in the earlier period) usually hostile towards Americans.  Their society also had a military flavor.  There were several subdivisions of various ranks, from boys in training to the retired veterans who acted as adviser and directors of the rites.  Each of these orders had its distinctive uniform and equipment, songs, and dance; and took charge of some special function at public gatherings.  There were also secret societies for the practice of medicine, magic, and special industrial arts.  The industrial societies were usually composed of women.  The ordinary dress in old times was of prepared deerskins.  The weapons were the bow, knife, club, lance, and shield.  Their principal deity was the sun, and a supernatural being known as "Napi" (Old Man).  Their marriages were easily broken (another reason polygamy thrived).  Their dead were usually deposited in trees, or sometimes in teepees that were erected for the dead on prominent hills.

The Blackfoot population of 1790 was around 8,500.  However, they suffered great losses due to smallpox in 1837, 1845, and 1869.  In 1883, about 600 on the Montana reservation died of starvation as a result of the failure of the buffalo and reduction of rations.  Their numbers were also reduced due to their continual wars.  The Blackfoot had no allies during their wars.  By 1906, their numbers were 4,617 souls.