With the Frankish conquest and the establishment of the Principality of Achaea, Karytaina became one of the secular baronies into which the Morea was divided by the Crusaders. Karytaina was one of the largest baronies, and of special strategic importance: its position allowed it to control the southern part of the mountainous Skorta region and, through the ravine of the Alpheios valley, the main route connecting the Arcadian plateau with the coastal plains of Elis. The barony belonged to the Briel or Bruyères family. The third baron, Geoffrey of Briel, built the Castle of Karytaina and played a major role in the affairs of Frankish Greece in the middle of the 13th century, repeatedly defying even the Prince William II of Villehardouin. After Geoffrey's death in 1275, the barony gradually reverted to the princely domain, and was later held by Isabella of Villehardouin and her daughter, Margaret of Savoy. From the late 13th century, Karytaina was increasingly threatened by the attacks of the Byzantine Greeks of Mystras, until it finally fell to them in 1320.