This splendid epic of 3750 lines has been preserved for us in a single MS in a handwriting of the fourteenth century. The first page of the MS is missing and it lacks two other pages within it. Fortunately, however, the main outline and significance of the lacunae can be restored from the Crónica de veinte Reyes de Castilla. To the indefatigable efforts of Menéndez Pidal we owe a debt of gratitude for the restoration of the text of the original MS to what this scholar thought must have been its original state. It is the general opinion that several MSS intervened between the extant MS and the original writing down of this poem. On the basis of internal evidence and general linguistic form the twelfth century is indicated and the accepted date of composition has been set at 1140. The language is Castilian. Attempts to designate it as Asturian on the basis of the assonances in o, ue have proved unconvincing.
A Mon, study studied this question.