The people of the Earth Kingdom are proud and strong and adhere to a philosophy of peaceful coexistence and cooperation with the other nations of the world. Earthbenders use their abilities for defense and industry and have fiercely defended their cities against attacks by the Fire Nation. The Earth Kingdom is the largest country in the Avatar World in both population figures and land area. Thus, it is an ethnically diverse country, with wide variance in customs between different provinces and tribes. It also has a large economy based on agriculture and limited industry, though it is not as economically powerful as the technologically advanced Fire Nation. Unlike the Air Nomads and Water Tribe, the Earth Kingdom did not suffer any sort of extinction in its civilization or its earthbenders during the Hundred Year War.
The Earth Kingdom long withstood encroachments on their borders in the Fire Nation's century-long imperialist war. Other than the Avatar, the Earth Kingdom was the only real obstacle between the Fire Nation and complete world domination, as the Water Tribes only demonstrated the ability to defend their own lands, the poles. Though the Water Tribes aided the Earth Kingdom in the War, the conflict progressed poorly and took a heavy toll on them as the years passed. This continued until the Coup of Ba Sing Se, when Princess Azula of the Fire Nation, took control of the Earth Kingdom capital city, Ba Sing Se. By the following summer, it was occupied by sparse Fire Nation forces which were plagued by rebellions, warranting the decision to burn the Earth Kingdom upon the arrival of Sozin's Comet.
During the arrival of Sozin's Comet at the very end of the summer, Ba Sing Se was liberated from Fire Nation control by the Order of the White Lotus, effectively ending the Fire Nation occupation of the city. This, in combination with the decisive defeat of Phoenix King Ozai, effectively liberated the Fire Nation-held parts of the Earth Kingdom.
After the end of the Hundred Year War, all Fire Nation colonies throughout the Earth Kingdom were transformed into the United Republic of Nations, a fifth nation founded by Avatar Aang and Fire Lord Zuko.
Seventy years after the conclusion of the Hundred Year War, the Earth Kingdom continues to be influential in world affairs with a representative on the United Republic Council.