As portrayed in El Cid
Despite these definite assertions of authorship by Gil Diaz and/or his nephew within the document itself, most scholars detect nothing Arabic in the style of the Chronicle, except the Lamentation for Valencia. They feel it is the work of a Spaniard who drew from Arabic source documents. Certainly the rather tedious listings of the price of commodities at various points during the siege sound like quotations from a chronicle kept by the Moorish bookkeeper who would later be the Cid's chief administrator...
Scholars have engaged in endless debates as to the actual age of the Chronicle. Portions of it appear nearly verbatim in the Chronicle of Spain assembled in the 13th Century. But the language of the Chronicle of the Cid is often more archaic than that of the Chronicle of Spain. No consensus has ever been sustained as to whether these common portions are both drawn from an Arabic original, or one is copied from the other. Various anachronistic references and mentions of events over a century later mean that the Chronicle is certainly not contemporary with the Cid, as the first publisher asserted. However it is generally agreed that it was written by the end of the thirteenth century, within 150 years of the Cid's death. That means that whatever legends exist in the Chronicle had arisen by that time.