The Grand Kingdom of Westmark could more aptly be titled an empire, since it is a confederation of eight petty kingdoms ruled by a single High King. One hundred years ago the Eight Kingdoms were united by King Robert Baratheon, the other 7 kings still held power in their domains but swore fealty to Robert and had their titles changed to "Lord of" whichever of the Eight Kingdoms they ruled. Those whom Robert trusted were sworn Wardens and allowed to maintain an army. Westmark is ruled from the city of King's Landing on the coastal plain. Robert tried in vain to add Everwinter as a vassal but he was soundly defeated by the Winter King's armies.