Born a princess, the oldest daughter of King Sancho I. Married to King Alfonso IX of Leon, Spain; northern Portugal formed part of her dowry. Mother of three children. Several years into the marriage it was dissolved by the Vatican upon the revelation that Theresa and Alfonso were cousins. Single again, Theresa returned to Portugal where she converted the Benedictine monastery at Lorvão into a convent for 300 Cistercian nuns. Theresa then moved into the convent, though she did not take vows. In 1231 she left to settle a bitter succession dispute between her children over the throne of Leon. With peace between them, she returned to the convent, took vows, and remained there as a nun for the rest of her life.