"What Are the Seven Kingdoms," You Ask? Here's Your Answer

As you may have guessed, this western kingdom is home to the Lannisters, though it was originally ruled by House Casterly. House Lannister took it over during the Andal invasion. It includes Kayce, Crakehall, and Lannisport, with Casterly Rock as its regional capital. Other important houses of the region include Blount, Clegane, Payne, Reyne, and Yarwyck. Its population almost exclusively follows the Faith of the Seven.