The Trastámara Dynasty was a royal family that ruled over Spain from the late 14th century to the early 16th century. It originated when Henry II of Castile overthrew the House of Burgundy in 1366. The dynasty is known for uniting the kingdoms of Castile and Aragon, which laid the foundation for modern Spain. Key figures of the Trastámara Dynasty include Isabella I of Castile and Ferdinand II of Aragon, whose marriage in 1469 united their kingdoms. This union was crucial in the completion of the Reconquista and the establishment of Spain as a significant European power.