On this day in world history in 1112, Duke Ramon-Berenguer III of Barcelona married Douce I of Provence. The two duchies, which were neighbors on the current French-Spanish border, were brought together by this marriage, increasing the wealth and power of their realms. Their son, Ramon-Berenguer IV of Barcelona, would marry the Queen of Aragon, Petronilla. This union would signal the beggining of Aragon’s golden age, as they began to expand, taking over the east coast of the Iberian Peninsula, and joining in a union with Naples later. Eventually, Aragon would join with Castile to create the Kingdom of Spain. As King of Aragon, Alfonso I, Ramon-Berenguer III’s son, became the first ruler of Aragon to rule from Barcelona, which would remain its capital until the founding of Spain.