Identified with the mountain range currently known as Sierra de Pela.
And they went on towards the Sierra de Miedes.
And he said unto them, Now take and eat, for we must pass this great and wild Sierra, that we may quit the land of King Alfonso this night.
So they passed the Sierra that night.
And at day-break they were near the brow of the Sierra, and they halted there upon the top of the mountains, and gave barley to their horses, and remained there until evening.
My Cid thought to take Alcocer: so he pitched his tents securely, having the Sierra on one side, and the river on the other, and he made all his people dig a trench, that they might not be alarmed, neither by day nor by night.