Berenguer IV of Barcelona was a prominent medieval nobleman who ruled as the Count of Barcelona from 1131 until his death in 1142. He was a member of the House of Barcelona and played a significant role in the expansion of the county's territory, particularly through military campaigns against the Muslim kingdoms in the Iberian Peninsula. His reign marked a period of growth and consolidation for the region. In 1137, Berenguer IV married Petronilla of Aragon, which united the crowns of Aragon and Catalonia. This marriage laid the foundation for the future Crown of Aragon, significantly influencing the political landscape of the region. His legacy is remembered for strengthening the ties between these two important territories.