Region in Burgos province.
And the Moors entered Castille, in great power, for there came with them five Kings, and they past above Burgos, and crost the mountains of Oca, and plundered Carrion, and Vilforado, and Saint Domingo de la Calzada, and Logrono, and Najara, and all that land; and they carried away many captives both male and female, and brood mares, and flocks of all kinds.
But as they were returning with all speed, Rodrigo of Bivar raised the country, and came up with them in the mountains of Oca, and fell upon them and discomfited them, and won back all their booty, and took all the five Kings prisoners.
When King Don Sancho of Navarre saw that there was a new King in Castille, he thought to recover the lands of Bureva and of Old Castille as far as Laredo, which had been lost when the King his father was defeated and slain at Atapuerca in the mountains of Oca.