In the 12th century, the need to counter occupation by the English and hold up the advance of Catharism resulted in a growth in the number of monasteries in the region, sheltering different religious orders. This period saw the construction of a number of new abbeys and the restoration of old abbeys using new architectural techniques. Stone vaulting, for example, was used instead of timbers as it was less vulnerable to fire. This new style of construction was known as Romanesque art, and is widthly represented in Périgord, where it corresponded with a period of repopulation and massive construction programmes. It is easily recognised from the simple, almost severe forms, carved out of the golden, light sandstone that is one the major assets of Périgordian architecture. In the 12th century there were as many as four hundred Romanesque churches in Périgord.