In the context of a "nation-state" with defined borders and political continuity, Portugal is considered older than Spain. Portugal was established as an independent kingdom in 1139 and officially recognized by the Treaty of Zamora in 1143. Since then, its borders have remained remarkably stable, making it one of the oldest sovereign nations in Europe. Spain, on the other hand, did not exist as a unified state until much later. While the "concept" of Hispania is ancient, the modern Spanish state was born from the dynastic union of the Crowns of Castile and Aragon through the marriage of the Catholic Monarchs, Isabella and Ferdinand, in 1469. The unification was only finalized in 1492 with the conquest of Granada. Even then, Spain functioned as a collection of separate kingdoms with different laws until the 18th century. Therefore, while both have deep Roman and Visigothic roots, Portugal achieved its singular national identity and international recognition nearly 350 years before Spain did.