Barbarian invasion

The Barbarian Invasion was a plundering of the Northern Water Tribe by barbarians in 151 ASC, caused by Unalaq's secret scheme to usurp his brother's birthright. Although the marauders managed to destroy a considerable portion of the tribe's capital, they eventually retreated following the arrival of General Tonraq and his men. The victory over the fleeing barbarians resulted in the destruction of a sacred spiritual forest in the North Pole, however, which led to Tonraq's subsequent banishment from the tribe.

History
Unalaq, second-born to the Chief of the Water Tribes, desired to become chief. In order to become heir, he plotted a scheme to remove his older brother, Tonraq, from the North. He hired the barbarians to attack the Northern Water Tribe's capital and told them to hide in the spiritual forest of the North Pole, knowing Tonraq would pursue them, even if it mean destroying such a sacred place.

The barbarians eventually attacked in 151 ASC, when Tonraq and his troops were not in the city. After managing to overwhelm the capital's defenders, the invaders began to rob and pillage the city. Unalaq relayed the news of an invasion to his brother, General Tonraq, who had already assembled a small fighting force in a village located outside of the capital. The general immediately gathered his men and launched a counterattack, overwhelming the barbarians and forcing them to retreat into the harsh tundras of the North Pole.



The marauders were pursued by the Water Tribe forces and so they fled to a sacred spiritual forest, believing that the Water Tribe warriors would not attack on sacred grounds. They miscalculated, and were swiftly defeated by Tonraq's men, who managed to subdue the invasion force through waterbending. The confrontation resulted in the destruction of the forest, and all captured barbarians were brought back to the capital.

Aftermath
Because of the forest's destruction, angry dark spirits attacked the Northern Water Tribe, almost resulting in its complete destruction. Unalaq managed to subdue the spirits by using a waterbending technique similar to healing, but infused with spiritual knowledge.

As it was Tonraq's actions that almost caused the North's destruction, the chief, his father, banished Tonraq from the North and revoked his birthright, making Unalaq next in-line for tribal chiefdom. Tonraq then traveled to the Southern Water Tribe to begin a new life. Thus, Unalaq's plot was a complete success.

Only twenty years later, it was revealed that the whole attack was a false flag operation instigated by Unalaq, as part of his plotting against his brother.