Gonzalo Fernández was Count of Burgos (ca. 899-915) and of Castile (c. 909-915). Recorded for the first time in 899 as Count of Burgos, soon the region expanded to the eastern mountain valleys enabling Gonzalo to make his fort base in Lara, thus stretching his rule from the foot of the Cantabrian Mountains around Espinosa de los Monteros to the river Arlanza, which therefore became the border with the neighbouring Muslim territories. In order to stretch his territory this far, he first had to displace the Muslim forces based at the stronghold of Carazo that dominated the area and access. This was achieved after a long and well contested struggle.