House Arryn is the principal noble house in the Vale; many lesser houses are sworn to them. Their main seat is at the Eyrie, but they have many other holdings. Their sigil is a white moon-and-falcon on a sky-blue field, and their words are "As High as Honor." Their line dates back to the old Andal nation that invaded Westeros. Usually marrying other Andal nobles, House Arryn to this day has the purest line of Andal nobility.
Prior to the arrival of the Andals, the Vale was ruled by the First Men under the Mountain Kings. Ser Artys Arryn slew the last of the Mountain Kings and the Arryns became Kings of Mountain and Vale. They renamed the land the Vale of Arryn, and their kings wore the Falcon Crown. They submitted to Aegon the Conqueror and house Targaryen, and became lords paramount of the Vale and Wardens of the East. During Robert's Rebellion, they supported Robert Baratheon.
ALLIED HOUSES: Stark, Tully
ENEMY HOUSES: Lannister