Duke of Gandia in the context of Tomás de Borja y Castro

The House of Barcelona was a medieval dynasty that ruled the County of Barcelona continuously from 878 and the Crown of Aragon from 1137 (as kings from 1162) until 1410. They descend from the Bellonids, the descendants of Wilfred the Hairy. They inherited most of the Catalan counties by the thirteenth century and established a territorial Principality of Catalonia, uniting it with the Kingdom of Aragon through marriage and conquering numerous other lands and kingdoms until the death of the last legitimate male of the main branch, Martin the Humanist, in 1410. Cadet branches of the house continued to rule Urgell (since 992) and Gandia. Cadet branches of the dynasty had also ruled Ausona intermittently from 878 until 1111, Provence from 1112 to 1245, and Sicily from 1282 to 1409. By the Compromise of Caspe of 1412 the Crown of Aragon passed to a branch of the House of Trastámara, descended from the infanta Eleanor of the house of Barcelona.

Gandia (Valencian: [ɡanˈdi.a], Spanish: Gandía [ɡanˈdi.a]) is a city and municipality in the Valencian Community, eastern Spain on the Mediterranean. Gandia is located on the Costa de Valencia, 65 kilometres (40 mi) south of Valencia and 110 km (68 mi) north of Alicante. Vehicles can access the city through road N-332 and AP-7 highway.

Gandia operated as an important cultural and commercial centre in the 15th and 16th centuries: in the 15th century it had a university. It was home to several important people, including the poet Ausiàs March (1400-1459) and the novelist Joanot Martorell (1410-1465). It is perhaps best known for the Borja or Borgia, through their family title, Duke of Gandia (originally created in 1399).