Until the 15th century, Spain was only a distant participant in the general movement of European affairs. The different kingdoms sharing the Spanish peninsula were individually too weak to pursue an energetic foreign policy (Mariejol 1961). The marriage of royal cousins, Ferdinand of Aragon and Isabella of Castille, in 1469 brought stability to both kingdoms. Both understood the importance of unity; together they effected institutional reform, such as in the Spanish Reformation, and left Spain one of the best administered countries in Europe.
