"Fire is the element of power. The people of the Fire Nation have desire and will and the energy and drive to achieve what they want. Earth is the element of substance. The people of the Earth Kingdom are diverse and strong. They are persistent and enduring. Air is the element of freedom. The Air Nomads detached themselves from worldly concerns and found peace and freedom… Water is the element of change. The people of the Water Tribe are capable of adapting to many things. They have a deep sense of community and love that holds them together through anything."
Several factors determine the prosperity of the four nations, such as political balance, economic success, societal order, and spirituality. In recent history, one of the greatest threats to global stability was the Hundred Year War, in which the Fire Nation sought to dominate over the other nations using military force, thereby disrupting peace. After the end of this conflict, relations between the different countries have significantly improved, and each of the four nations had a representative on the United Republic Council, until the council was abolished in early 171 ASC.
- Main article: Water Tribe
The Water Tribe is a sovereignty of waterbenders and other tribal people. There are three tribes: the Northern Tribe, the Southern Tribe, and the Foggy Swamp Tribe, whose people inhabit the North Pole, the South Pole, and the Earth Kingdom's Foggy Swamp, respectively. Both the Northern and Southern Tribes are chiefdoms, with the North currently ruled by Chief Unalaq. They were formerly ruled by Arnook and Hakoda, respectively. The Foggy Swamp tribe on the other hand, seems to have no official leadership. Members of the tribe seem to just live in scattered communities across the swamp.
The Northern Tribe is much stronger than its sister tribe, due to a larger number of its people being benders. The Southern Tribe did not have as many waterbenders and subsequently fell victim to attacks by the Fire Nation. The tribe was deeply affected by the damages that were caused, and ultimately only one bender remained, that being Katara.
They are occasionally referred to collectively as the Water Tribes. Generally, the Water Tribes do not mingle with the other nations, but seeing that a pirate salesman called out, "Earth Nation! Fire Nation! Water Nation!", there are at least some Water Tribe members traveling the world.
- Main article: Earth Kingdom
The Earth Kingdom is the largest and most diverse of the four nations, its people strong and proud, with some of them being earthbenders. Their land is comprised of a massive continent in the eastern hemisphere and several islands. The Earth Kingdom is extremely diverse, having mountainous, forested, grassland, desert, and man-conquered areas, including the vast megacity Ba Sing Se. Due to its peoples' bending ability, the people of the Earth Kingdom have created magnificent structures out of stone, such as the city of Omashu.
The Earth Kingdom is run overall as a monarchy, the capital being Ba Sing Se. However, it is apparent that there are smaller regions and cities with their own rule, such as Omashu, which was ruled by King Bumi, captured by the Fire Nation, and later restored again by Bumi.
It is sometimes referred to as the Earth Nation.
- Main article: Fire Nation
The Fire Nation is the second largest nation, and home to most known firebenders. It is located on an archipelago of islands located in the western hemisphere of the planet and is the most advanced of the four nations, with steam and gas power. It started out with a huge fleet of industrial war ships, and later on adopted the use of airships into its military.
The Fire Nation is also diverse in landscape, featuring many volcanic islands in its archipelago and on the mainland, as well as a tropical climate. It also has the world's most popular vacation spot, Ember Island.
The country is an absolute monarchy and could even be called a dictatorship. In 0 ASC, the Hundred Year War was started by Fire Lord Sozin, using his country's advanced technologies. During the Hundred Year War, its people were oppressed and fed propaganda by rulers Sozin, Azulon, and Ozai. However, in 100 ASC, the Fire Nation's conquest was ended and a new era of peace began, with Zuko as the new leader.
- Main article: Air Nomads
The Air Nomads were the collective of the airbender people. Though the people of this nation were nomadic, the Air Nomads raised children and situated their central governments in four monastic temples located at various ends of the globe, two for males and two for females. The four air temples are located on small archipelagos that were Air Nomad land on the tip of mountains and, in one case, hanging under cliffs.
The Air Nomads were loosely run by elder councils, one male and one female. Their people were extremely spiritual.
In 0 ASC, the Fire Nation executed a mass invasion and genocide of the Air Nomads, driving the nation into near extinction save for Avatar Aang, who managed to escape. It is sometimes referred to as the Air Nation in Fire Nation propaganda.