The Tsuu T'ina Nation, formerly Sarcee, Sarsi.

is a First Nation in Canada.

Their territory today is confined to the Tsuu T'ina Nation 145 Indian reserve, whose east side is adjacent to the southwest city limits of Calgary, Alberta although their traditional territory was much more extensive.

The land area of the reserve is 283.14 km² (109.32 sq mi), and it had a population of 1,982 in the Canada 2001 Census.

The northeast portion of the reserve formed part of CFB Calgary, a Canadian Army base from 1910–1998.

In 2006, the land was returned to the Nation by the Government of Canada.

The Tsuu T'ina people were formerly called the Sarsi or Sarcee, words which are believed to have been derived from a Blackfoot word meaning stubborn ones.

This is in reference to territorial conflict between the Tsuu T'ina and the Blackfoot Confederacy.

The proximity of the territory to the City of Calgary had led to disagreement over the Province of Alberta's plans to construct the southwest portion of a ring road, referred to as Stoney Trail (Highway 201), a freeway which encircles the City of Calgary and which must pass through Tsuu T'ina land to avoid environmentally sensitive areas.

A 2009 referendum by the Nation rejected a plan to transfer reserve land to the Province of Alberta to permit construction of the southwest portion of the ring road.

Some members of the Nation were upset by the rejection of the land transfer, while others viewed it as a triumph both environmentally and for the Nation.

A subsequent referendum held by the Nation in 2013 approved the land transfer for the ring road.

In 2007, the Tsuu T'ina opened the Grey Eagle Casino just outside city limits.

The Grey Eagle complex began a major expansion, including construction of a hotel, in 2012.

Both the initial construction of the casino and the expansion have been accompanied by concerns about traffic tie-ups in the area of the casino.