Three hundred years before the novels begin, the Targaryen dragonlord Aegon the Conqueror and his two sister-wives Visenya and Rhaenys, whose ancestors migrated from Valyria to Dragonstone a century prior, invaded the Westerosi mainland and landed his army at the mouth of the Blackwater Rush. The three assembled a temporary bastion called "Aegonfort", which later grew into the a massive capital city known as King's Landing. Aided by their three formidable fire-breathing dragons, the Targaryen armies subdued six of the Seven Kingdoms through conquest or treaty, wiping out three of the seven ruling houses (Durrandon, Hoare and Gardener). Only the defiant Dorne remained independent for another two hundred years through asymmetric guerrilla resistance, until it was finally absorbed under the Iron Throne through a marriage-alliance by King Daeron II. The Targaryens built the Iron Throne, forged from the swords of their defeated enemies by dragonfire. They also annexed the land regions of the riverlands and stormlands around the Blackwater Bay as the Crownlands. House Targaryen ruled as the sole monarchy of the Seven Kingdoms for almost three centuries until overthrown by a rebellion led by Robert Baratheon in 283 AC.