The capital city of the Kingdom moves in 1118 to Zaragoza.

By 1285, the southernmost areas of Aragon has been taken from the Moors.The Kingdom of Aragón gives the name to the Crown of Aragon, after the dynastic union in 1150 of a Count of Barcelona (Ramon Berenguer IV) with a Queen of Aragón (Petronila of Aragon), their son inheriting all their respective territories.

The Kings of Aragón have also the title of Count of Barcelona and rule territories that consist not only of the present administrative region of Aragon but also Catalonia, and later the Balearic Islands, Valencia, Sicily, Naples and Sardinia (see Crown of Aragon).

The King of Aragón is the direct King of the Aragonese region, and holds also the title of King of Valencia, King of Majorca (for a time), Count of Barcelona, Lord of Montpellier, and, for a time, Duke of Athens and Neopatria.

Each of these titles gives him sovereignty over a certain region, and these titles change as he loses and wins territories.

In the fourteenth century, his power is greatly restricted by the Union of Aragon.The Crown of Aragon is effectively disbanded after the dynastic union with Castile which supposes the de jure unification of the Spanish Kingdom after some time of de facto unification under a common monarch.

After this happens, Aragon keeps some political institutions, until the Nueva Planta decrees, promulgated in 1707, finally put an end to it.