I. The Omen
Twenty millennia have passed since the Dark Lord Sauron was defeated by the Fellowship of the Ring. The people of the twenty fourth age had reached an era of industrialization. The animals that still roamed the wild evolved into creatures that were made out of two species. People even began to bend the four elements of water, earth, fire, and air and eventually nations were formed out these different practices: The Air Nomads, the Water Tribe, the Earth Kingdom, and the Fire Nation. The Air Nomads were a race of monks who lived a spiritual life in the high mountains. The Water Tribe was made up of two tribes, one in the North Pole and the other residing in the South Pole. Their culture relied on water and ice and had little use for machines. The Earth Kingdom was comprised of individual kingdoms spread out all over the land. Their palaces and cities were built entirely out of earth and they also had no need for modern technology. The Fire Nation, however, was the most industrialized race located on a large land mass surrounded by volcanic islands. Together the four nations shared peace and harmony that had lasted for hundreds of years.
But this peace did not last forever. The era of peace ended when a comet from outer space flew over the Fire Nation. With the appearance of this comet, the Fire Nation's ruler, Fire lord Sozin, had a vision of the world that existed twenty thousand years ago. In his vision, he witnessed a history beyond his knowledge. It revealed a story about a Dark Lord known as Sauron. This deceptive, powerful, warrior-king launched a conquest of the world with massive armies and a special tool of his own making that gave him ultimate power. It was known as the One Ring of power, into which he poured his will to dominate all life. The ring had been lost after a battle and it was found by his enemies, the free peoples of that land. A brave group called the Fellowship of the Ring, which was made up of all the races of the land, set out to destroy the ring where it had been made, in Sauron's dark kingdom of Mordor. His forces battled them relentlessly, nearly destroying them. Yet, through great determination and reliance on one another, the Fellowship of the Ring succeeded in destroying the ring, ending Sauron's plans for world domination. However, during his downfall Sauron was able to use the remaining part of his dark magic to set a future rise to power in motion. He poured half of it into creating a second ring of power; a ring that was far stronger than the previous one. The last of of his power was used to grant certain creatures the ability to bend elements, and after many generations man would learn the art of bending from them. Once the Dark Lord's magic was gone, he faded away, but his spirit endured as long as the new ring survived. Fire Lord Sozin could not see in his vision where the ring had been hidden, and then his vision ended.
Now that Sozin knew this missing part of his people's heritage, he was bewildered and began to imagine a new destiny for his nation. He realized that man's ability to bend the elements was a gift from the Dark Lord. The Air Nomads learned airbending from flying creatures called sky bisons. The Water Tribe learned waterbending from the Moon Spirit who took the form of a Coi fish. Huge earth creatures known as badger moles had taught the people of the Earth Kingdom the ways of bending earth. Sozin's great Fire Nation had acquired the art of firebending from the dragons who had survived the many ages. The very existence of the four nations was a result of Sauron's magic. Fire Lord Sozin now felt a sense of allegiance to this Dark Lord and believed that the vision was a sign to take on Sauron's will and fulfill his rise to power.
After informing his chief advisers of the significance of his vision, he began a new plan for the nation. He would conquer the other nations under the banner of the Fire Nation, to prepare the world for the coming of Sauron. In doing so, he would search for the One Ring and protect it until the time of the Dark Lord's return. Sozin and his army of fire benders, using their breath of chi were able to harness the power of the comet as it burned in the heavens and this increased their bending abilities to a level greater than ever before. With their new strength, the Fire Nation declared war and began to attack the other nations one by one.
During this time of war, the Air, Water, and Earth nations believed that a spiritual being, with the power to bend all four elements could stop the Fire Nation and restore peace. This spiritual being was called the Avatar. It was known that the Avatar had appeared in different generations and in each of the nations. But at this time of war he had not appeared. The Fire Nation was aware that the Avatar would likely be born into the Air Nomads so they concentrated their fire power on eliminating the air bending monks. But the Avatar could not be found in the attack. The Fire Nation took control over most of the world, but the comet's power was temporary so their ability diminished and they could not finish the war. Ever since that time the Fire Nation was considered an enemy to the other civilized nations. They would continue to worship Sauron as a god and carry out the preparations for his return to the world.