Aidan is a continent that comprises the easternmost part of Tane's western supercontinent.
During the Pre-Caspian Era, the continent lived in a state of anarchy. Clans and kingdoms were constantly warring with each other over resources and territory. In 345 PC, the Telmarine Empire conquered the lands of Aidan, enslaving the various humans and beastfolk which inhabited the continent. This continued for over three hundred years, until an exiled Telari noble named Caspian formed an army of barbarians, escaped slaves and Dwarven warriors from the Three Kingdoms. Eventually, the imperial capital of Colov had fallen to Caspian's Army, though Caspian himself disappeared not long after the siege. After Caspian's disappearance, his trusted advisor Lord Bern met with Caspian's other generals and Telari leaders who seemed sympathetic to his cause. Together, they divided Aidan and southern Cotera among themselves, establishing the first modern kingdoms.
In 1 PC, Caspian's teachings were organized into a monotheistic religion known as Katholism, which was established by King Remi I of Lyonesse. As time went on however, the Katholian Church had perverted Caspian's teachings, making them more conservative and human-centrist than Caspian had intended. During the Third Era, a man named Rylan stood in front of the Grand Cathedral and began addressing the crowds. He claimed to be Caspian's son and said that the Katholian Church strayed from the path that Caspian envisioned. When the Lyonean emperor Rishleau II ordered Rylan's arrest, he fled to the neighboring kingdom of Camelot. When the King of Camelot refuses Emperor Rishleau's demands to return Rylan to his kingdom, the Emperor invades Camelot and lays siege to its capital. After fourteen days, the armies of the kingdoms of Vael and Halamshiral stormed the Lyonesse camp and broke the siege of Camelot.
The Hundred Year War that resulted from the battle pitted Lyonesse and several surrounding kingdoms against the forces of Camelot and several kingdoms in Eastern Aidan and Northern Cotera. The war continued until the rise of Grand Holy Father Aran IV, who called for peace between the Katholian Church and the Rylanites. Today, there is peace between the two faiths, though it is tenuous at best.