structural:expansion, quality:corruption
Union of the Crowns of Aragon and Castile and afterwards

The Crown of Aragon became a part of the Spanish monarchy after the dynastic union with Castile, which supposed the de facto unification of both kingdoms under a common monarch. The house of Barcelona held the Crown until 1410, when it went extinct. Subsequently, in 1412 the Aragonese secured the election of a Castilian prince, Ferdinand of Antequera, to the vacant Aragonese throne, over strong Catalan opposition. One of Ferdinand's successors, John II of Aragon (1458–1479), countered residual Catalan resistance by arranging for his heir, Ferdinand, to marry Isabella, the heir presumptive of Henry IV of Castile.

In 1479, upon John II's death, the crowns of Aragon and Castile were united to form the nucleus of modern Spain. Aragonese territories retained their autonomous parliamentary and administrative institutions, such as the Corts, until the Nueva Planta decrees, which were promulgated between 1707 and 1715 by Philip V of Spain in the aftermath of the War of the Spanish Succession. The decrees de jure ended the kingdoms of Aragon, Valencia and Mallorca, and the Principality of Catalonia, and merged them with Castile to officially form the Spanish kingdom. A new Nueva Planta decree in 1711 restored some rights in Aragon, such as the Aragonese Civil Rights, but upheld the end of the political independence of the kingdom.

The previous Kingdom of Aragon remained as an administrative unit until 1833, when it was divided into the three existing provinces. In the aftermath of Francisco Franco 's death, Aragon became one of the autonomous communities of Spain in 1982.