Prior to the Treaty of the Pyrenees in 1659 , most of the present department was part of the former Principality of Catalonia , within the Kingdom of Spain , so the majority of it has historically been Catalan-speaking , and it is still sometimes referred to as Northern Catalonia .
Before 1659 , most of the present department was part of the former Principality of Catalonia , within the Kingdom of Spain , so historically most of it has been Catalan-speaking , and it is still sometimes referred to as Northern Catalonia .