Ancestry
 

Traditionally the Tsuu T'ina were organized into a series of bands, each composed of a number of closely related families that often hunted and camped together either alone or with bands of the "Blackfoot" tribes. The Tsuu T'ina bands would come together in the summer for the annual religious ceremonies, most important of which was the holding of the annual "Sundance". Each band was led by a "chief". The most efficient leader and greatest warrior was by common consent the "tribal chief".

Tsuu T'ina populations fluctuated considerably during the last two centuries, as smallpox and other epidemic diseases swept across the Northern Plains at regularly recurring intervals beginning with the first epidemic in the 1730's. In 1810, the Nation recovering from the smallpox epidemic of 1781 was estimated to consist of 90 tents( approximately 420 people). By 1832 their population had more than doubled, probably approximating their number prior to the epidemic of the 1730's. Smallpox swept through the plains in the spring of 1835, killing over half the population. Smallpox struck again in 1869. In 1871 their population was estimated at 408.