House Lydden of the Deep Den traces its origins to the great Andal migration that swept across Westeros in the centuries before the Targaryen Conquest. Their ancestors were Andal adventurers who carved holdings out of the western hills, securing a fastness at Deep Den along the Goldroad, south of Hornvale and north of Silverhill. The house rose to singular prominence when Ser Joffrey Lydden, having wed the only daughter of King Gerold III Lannister, was crowned King Joffrey Lannister upon the king's death without male heirs, making him the first Andal King of the Rock. Though the Lydden name receded behind the Lannister style, the connection bound the two houses irrevocably, and the lords of Deep Den have remained among the most trusted bannermen of Casterly Rock ever since.
At the onset of A Game of Thrones, Lord Lewys Lydden answers Lord Tywin Lannister's call to arms and leads his levies into the riverlands as part of the great host sweeping east. The Lydden men fight in the centre under Ser Kevan Lannister at the Battle of the Green Fork, and Lord Lewys is counted among the western lords present at King Joffrey I Baratheon's first court audience following the Battle of the Blackwater. Sansa Stark names the Lyddens alongside Houses Brax and Crakehall as great lords of the west, a mark of the house's enduring standing among the nobility of the westerlands.