The word "tribe" connotates a lack of cohesive political, cultural and social structure which definitely does not apply to the Niitsitapi. In fact, the cohesive structure was the very reason that the Niitsitapi achieved cultural, political and military predominance making them "the Lords of the Great Plains." They were a Nation of people united by a common language, culture and religion living in a country with borders recognized by other First Nations. When the Canadian federal government entered into negotiations with Crowfoot, the Siksika political leader, he had to consult the other Niitsitapi leaders as he was being asked by the government to negotiate matters affecting all Niistitapi. As leader of the Siksika and not the entire Niitsitapi, he couldn't do so without the consent of the other leaders.
In 1870, one of the worse slaughters of Indians by American troops occured, known as the Marias Massacre. On the morning of Jan. 23, 200 Peigans were killed, most of them women, children, and elderly. The Peigans were a friendly tribe, not the hostile camp that the troops were supposed to attack. However, the commander had permission to use his judgment and attack the Peigans and punish them for things they may be guilty of in the past or future. After the massacre, the troops left to find their real target, but it was too late as the hostile tribe had moved.
In daily life the Blackfoot were a nomadic people who followed the buffalo. It's difficult to lead a nomadic lifestyle when there is no place to go. The Niitsitapi were hemmed in by other First Nations. In addition, the different Niitsitapi had claim to areas within Niitsitapiskaku, for instance, the Siksika couldn't infringe on Ahkainah territories as the Ahkainah lived there. Their territory once covered an areas from Edmonton and Calgary, Alberta to the Yellowstone River, and from the Rocky Mountains to the present day North Dakota border.