The Water Tribe is the nation of Waterbenders and their people. This nation is divided into two tribes, the Southern Water Tribe, which inhabits the South Pole, and the Northern Water Tribe, which inhabits the North Pole. There is also the Foggy Swamp Tribe, a tribe of Waterbenders who reside in swamps of the Earth Kingdom.
The government of the Water Tribe is run by two separate entities, the loosely held chiefdom of the Southern Water Tribe, and a more monarchic chiefdom in the Northern Water Tribe. It is unknown how and why the Waterbenders split into two Tribes.
It is occasionally referred to as the Water Nation. Generally, the Water Tribes do not mingle with the other nations, but, as seen in The Waterbending Scroll where the pirate calls out "Earth Nation! Fire Nation! Water Nation!", there are a significant amount of Water Tribe members also travelling the world.