In June 1524, Spanish forces led by Pedro de Alvarado entered the central-western territories of present-day El Salvador. The region was inhabited by the Pipil, a Nahua-speaking people whose pre-Columbian population has been estimated at around 200,000. Politically organized into a network of city-states, headed by the one of Cuzcatlan, the Pipil mounted fierce armed opposition to the invaders. Two major battles, at Acajutla and Tacuzcalco, inflicted significant losses on the Spanish expedition, forcing its withdrawal to Guatemala after a month of campaigning. The Spaniards returned in early 1525 and founded the settlement of San Salvador as a strategic foothold for the gradual conquest and colonization of the region, following a pattern employed elsewhere in the Americas. Indigenous resistance, however, remained strong. In 1526, Pipil forces attacked and destroyed the fledgling settlement, while widespread guerrilla warfare prevented effective Spanish control. Two further military expeditions were required to reassert the conquest. San Salvador was refounded on 1 April 1528, and by the end of that year most of the territory, including the indigenous city of Cuzcatlán, had fallen under Spanish domination. The exception was the rocky fortress of Peñon de Cinacantán, where many Pipil warriors continued to resist. Only in January 1529 did the Spanish capture the position after a fierce battle. Many defenders were killed, while others escaped into inaccessible areas. Most survivors were subsequently concentrated into reducciones and assigned to encomiendas. Sporadic indigenous uprisings nevertheless continued, including those in Nahuizalco and Masahuat (1529), in the coastal Bálsamo area (1533), and in Izalco (1553). Obs: This AI-authored synopsis was reviewed and edited by the Editors to ensure accuracy and reliability. It should be understood as provisional, awaiting completion or replacement by one of our qualified contributors.