Count Ramón Berenguer IV was a prominent medieval nobleman who ruled as the Count of Barcelona from 1131 until his death in 1162. He played a crucial role in the expansion of the County of Barcelona and was instrumental in the unification of the Crown of Aragon. His reign is noted for significant territorial gains and the strengthening of feudal power in the region. Ramón Berenguer IV is also known for his marriage to Petronilla of Aragon, which helped to solidify alliances between the County of Barcelona and the Kingdom of Aragon. This union laid the groundwork for the future Crown of Aragon, influencing the political landscape of the Iberian Peninsula.