Located roughly in the center of the continent, and with few geographical boundaries such as mountains, for centuries it has been a borderland between surrounding strong kingdoms. The Riverlands were ruled by the ironborn at the time of the Targaryen Conquest, and Aegon the Conqueror's assault was assisted by a popular uprising led by House Tully. For this reason the Riverlands didn't have a king at the time of the invasion, and the Riverlands are not technically counted as one of the "Seven" Kingdoms (instead essentially making up the eighth "kingdom") . However, for administrative purposes, the Riverlands and their rulers are equal to any other region of the realm.