Water Tribes

The Water Tribes are one of the four nations featured in the Avatar: The Last Airbender franchise 
It is also a collective term for the nation of people who practice the art of waterbending. Many people of Water Tribe ethnicity also live in the United Republic and there is a small community of waterbenders that populate the Foggy Swamp in the Earth Kingdom, although they were isolated from their sister tribes for generations and others were largely unaware of their existence until they were stumbled upon by Avatar Aang, Katara, and Sokka. 
The people of the Water Tribes are referred to as "Water Tribesmen".