The first Avatar is created when Raava fuses with Wan.
The era of the first group of Avatars ranging from Avatar Wan to the "last" Avatar killed in The Great War.
The first Avatar is created when Raava fuses with Wan.
The last group of people to live solely on the backs of Lion Turtles finally depart into the greater world, ending the era of civilizations and nations on the backs of Lion Turtles.
The first era of Benders gaining prominence in the world. It is now common to encounter a Bender in any part of the world.
The first major region-spanning nations/empires are formed, partly through conquest, partly through diplomacy. The two most powerful of these are the Sun Nation (ancestors of the Sun Warriors) and the Water Nation (ancestors of the Water Tribes).
Benders on the main continent of Earth (ancestors of Earth-Benders) begin to rebel against both the Sun Nation (now known as the Sun Empire) and the Water Nation empires.
The first major all-bender confrontation in battle in world history occurs between warriors of the Sun Empire and the mainland rebels. The battle takes place at high noon, allowing the Sun Empire's early form of fire-bending to easily defeat the proto-earth-bending rebels.
The rebelling peoples on the earth mainland negotiate a treaty with the Water Nation that pushes the Water Nation empire off the earth mainland and onto the north and south poles - where they stay to the era of ATLA.
The earliest Air-Benders are caught in the cross-fire of The Bending War and are quickly killed off. The original practice of Air-Bending is seemingly lost with the death of the last Air-Bender...
The Bending War ends with the almost total annihilation of the Sun Empire and the independence of the earth mainland. Instead of consolidating into one nation, the newly freed peoples decide to form their own mini nations amongst themselves.
A group of scientists and historians dedicated to preserving past knowledge in order to use it in discovering future knowledge come together to form a society known as "The Secret College." It's not necessarily kept secret from the rest of the world, but the society limits its membership to only a select few scholars.
Peoples of the earth mainland begin migrating to the isles west of the mainland (the Fire Nation islands in ATLA). The migrants discover the abandoned old kingdom of the Sun Nation. They also discover dragons on some of the islands. The migrants permanently settle the "Fire Isles" as they're named and begin to learn fire bending by observing dragons.
The settlers of the "Fire Isles" form tribes and mini-nations which come into military conflict with one another. This is the era of warlords on the Fire Islands. It would last for 250 years. Notable warlords during this era include Toz (the first warlord to attempt to unify the Fire Islands) and Aizosum (the First Fire Lord).
The future founder of the Fire Nation is born. The Fire Sages in ATLA simply refer to him as "the first Fire Lord."
The settlement that would one day become the city of Omashu is established and begun to be built up.
Aizosum ends "The Fire Wars" by uniting the Fire Islands and declaring himself "Fire Lord." Under his leadership, the united Fire Islands enter the world stage as the newly established Fire Nation. An era of rapid economic and civic growth on the Fire Islands ensues.
A group of pacifist Fire-Benders breaks off from the Fire Nation in order to become solitary monks. During their travels, these people rediscover the lost arts of Air-Bending and eventually develop their own form of Air-Bending based on a mix between Fire-Bending and ancient Air-Bending. The so-called "Air-Nomads" begin settling in the mountains on the northern mainland and build the Northern Air Temple.
The Northern Air Temple is built thanks in part to the help of the Fire Nation.
The Eastern and Southern Air Temples are built and populated. The Air Nation now has significant sway in global politics thanks to potential trade and knowledge which can be gained by the different nations.
The 300 year long world-wide conflict simply known as "The Great War" begins. It spans the entire earth mainland and affects the Water Tribes, Air Nation, and Fire Nation as well. The fighting is mostly between the dozens of kingdoms on the earth mainland. Over time, this conflict grows to almost apocalyptic proportions, reaching levels of devastation not since since the era of Avatar Wan. Entire towns, cities, and even civilizations are destroyed during this war. Scholars estimate that the world's population was reduced by up to one-half. Benders almost go extinct.
The Avatar is killed in battle, defending one of the numerous innocent earth villages caught in the crossfire of war. A new Avatar would not emerge to the wider world for nearly 200 years, so this Avatar is nicknamed "the last Avatar."
The Avatar's death causes other benders defending innocents like her to lose hope. A few benders in the war sense that things will only get much worse and decide to go into hiding indefinitely. New Avatars are born among the benders over the years, but the benders still wait for the right moment to reveal themselves. They wait for nearly 250 years.
The era where no Avatar was known or active in the world.
The 160 year long siege of the Si Wong Oasis begins. The pre-courser civilization of the Sand Tribes holds out valiantly against the siege of numerous allied earth kingdoms for over a century, but eventually falls to the opposing earth kingdoms after decades of continual military campaigns in the region. The entire civilization is razed over time.
The kingdom which would eventually found the city of Ba Sing Se earns a decisive victory against their neighboring enemy, ensuring that this kingdom will survive the war once all is said and done. By the time of Before the Avatar... (BtA), Ba Sing Se commemorates the victory every year in a spectacular ceremony.
The last benders still fighting in the Great War are killed off. Those remaining who did not seclude themselves initially at the Avatar's death are hunted down and killed. For all that anyone knows, the practice of Bending has been lost forever...
The siege of the Si Wong civilization ends in its total annihilation, save for a few survivors who would shortly after form the Sand Tribes. The razing of Si Wong is so intense, the oasis is completely dried up and thus, the Si Wong Oasis became the Si Wong Desert by the sieges' end.
An alliance of southern earth kingdoms begin invading the Fire Isles in hopes of expanding their influence across the ocean. The initial invasion over time turns into a series of raids, sacking, and looting over a period of 100 years. The Fire Nation's economy is crippled by the continual raiding.
The Avatar, a woman named Gan, and thousands of benders reemerge from hiding and reveal themselves to the world. Avatar Gan leads the benders into the fray to defend innocent towns, villages, and cities caught in the crossfire of the war, following in the footsteps of their ancestors 200 years ago.
Oma, of the legendary tale of Oma and Shu, is born.
Oma and Shu defend the precursor village to the city of Omashu in ATLA from attackers during The Great War. Shu is killed in the fighting, but the defense is successful. As thanks, the villagers crown Oma "Queen" of the village.
The Great War finally ends on the earth mainland thanks to the heroics of Avatar Gan and the reemerged benders. By the wars end, no one alive remembers what the war was originally started over... In the same year, a fragile peace is established between the Earth and Fire Nations by treaty. Trade resumes between the Fire Nation and the earth mainland.
Though technically the Avatar revealed herself to the world again many years prior, the end of The Great War is seen as a beginning of a new era.
Convinced by Avatar Gan that the Fire Nation must reform its culture to become more peaceful, the peoples of the Fire Isles reorganize themselves into an Imperial Republic. An emperor type figure, the Lord-Governor, presides over a democratically elected senate body which makes the laws for the Fire Isles. The republic is remarkably more peaceful than its preceding form of government.
Xeno, future King of Ba Sing Se and High King of the United Earth Kingdoms, is born to a lowly noble in the King of Ba Sing Se's court.
Xeno would work his way up to eventually become the King of Ba Sing Se's right hand man. By seemingly sheer happenstance, all of the King's heirs die while Xeno is in the King's service. With no one else to hand the kingdom too, Xeno is crowned King.
A number of kingdoms on the Earth mainland (built up in part by the efforts of the Order of the Lotus) consolidate to form The United Earth Kingdoms. Xeno, King of Ba Sing Se at the time, is appointed High King of the United Earth Kingdoms by the Order of the Lotus. Xeno is then invited to become a member of the Order of the Lotus.
Avatar Gan dies. However, the Order of the Lotus decides to keep her death a secret so as to not cause panic in the world. The Order of the Lotus begins to discretely look for the new Avatar. Avatar Gan was so old when she died, no one remembered the original element she bent. So, the Order looks for the Avatar among all four major elements in the world.
The Peninsulan War, also known as the Peninsulan Civil War, begins when the tribes of the Eastern Peninsula rebel against their overlord, the United Earth Kingdoms. The guerrilla tactics of the Peninsulans would prove too much for the forces of the United Earth Kingdoms to overcome outright. So, the United Earth Kingdoms opted instead to wage a war of sabotage and attrition in hopes the Peninsulans would eventually surrender.
Xeno is elected leader of the Order of the Lotus. He radically transforms the order's structure, vesting the majority of the order's power unto himself, much to the chagrin of the other world leaders.
The head of the Order of the Lotus, Xeno, stops the training of the four Avatar candidates. Xeno instead declares himself protector of the world and vows to stop anyone who tries to "bring the Avatar back."
A few world leaders who are distrustful of Xeno decide to secretly establish the Order of the White Lotus and vow to train the Avatar before Xeno and the Order of the Lotus can. The three founding members are: Huraal of the Air Nomads, Sunaret of the Sand Benders, and Caedis of the Blood Benders.