According to several scholars, the term "Catalan" and "Catalonia" emerged near the end of the 11th century and appeared in the "Usatges" of 1150. Two factors fostered this identity: stable institutions and cultural prosperity. While the temporary lack of foreign invasions contributed to Catalonia's stability, it was not a major cause. Rather, it provided a zone for sociopolitical development. For example, after the County of Barcelona signed an agreement with the Kingdom of Aragon, to create the Crown of Aragon in 1137 through a dynastic union, the system was designed to mutually check both the king's and the nobility's powers, while the small but growing numbers of free citizens and bourgeoisie would tactically take sides with the king in order to diminish typically feudal institutions.