He was born Sebastián Moyano in the province of Córdoba, Spain, in either 1479 or 1480. He took the name Benalcázar as that was the name of the castle-town near to his birthplace in Córdoba. According to various sources, he may have left for the New World with Christopher Columbus as early as 1498, but Juan de Castellanos wrote that he killed a mule in 1507, and fled to Spain for the West Indies due to fear of punishment, and as a chance to escape the poverty in which he lived.