The North - House Stark (Winter is Coming)
The Starks ruled the North until the betrayal of Robb Stark at the Red Wedding by Roose Bolton.
The Vale - House Arryn (As high as honor)
The Vale has been ruled by the Arryns since forever from their castle known as The Eyrie.
The Riverlands - House Tully (Family, duty, honor)
The Riverlands are ruled by House Tully from its seat at Riverrun.
The Stormlands - House Baratheon (Ours is the fury)
The Stormlands were captured by Orys Baratheon, Aegon Targaryen’s bastard half-brother, during the War of Conquest.
The Westerlands - House Lannister (Hear me roar!)
The Westerlands were known as the Kingdom of the Rock until before the Targaryen conquest.
The Reach - House Tyrell (Growing strong)
The Reach is ruled by House Tyrell of Highgarden. It is the most fertile and most populated kingdom of Westeros, supplying livestock, wine and foodgrains to rest the of the lesser fertile kingdoms.
The Principality of Dorne - House Martell (Unbowed, unbent, unbroken)
Dorne has been ruled by House Martell of Sunspear. After the assassination of Doran Martell, the region is now under the control of Ellaria Sand, Oberyn Martell’s paramour.
There are also the Iron Islands ruled by House GreyJoy - We do not sow.