La Bureba
García Sánchez inherited the crown of Pamplona after the death of his father Sancho III in 1035, bypassing the late king's eldest son Ramiro, who was illegitimate. In 1043 he defeated his half-brother in battle, setting the eastern border of the kingdom. García Sánchez III took advantage of the weakened state of the numerous Islamic taifa kingdoms that arose after the dissolution of the Caliphate of Córdoba to push the southern border over their territory, taking the city of Calahorra in 1045. He also inherited from his father the County of Álava and a great part of the County of Castile (La Bureba, Trasmiera, Montes de Oca, the Encartaciones and Las Merindades).