 In the late 1204 the chateau was fortified to guard the southern frontier.In the Middle Ages the Montségur region was ruled by the Counts of Toulouse, the Viscounts of Carcassonne and finally the Counts of Foix.In 1243–44, the Cathars (a religious sect considered heretical by the Catholic Church) who had sought refuge at the Montségur fortress were besieged by 10,000 troops, in what is now known as the siege of Montségur.