The critic who wishes to trace the complete sequence of motivations in the Cantar de mio Cid is at a disadvantage, since the sole surviving poetic manuscript is acephalic, lacking one folio and thus probably about fifty lines of text. To approximate the poet's conception of King Alfonso's intention in proclaiming the exile with which the manuscript opens, one must have recourse to the Crónica de veinte reyes, which contains the prosification whose text is closest to the poem (text in Menéndez Pidal 1954–56,1:1022–4; Dyer 1975 begins her text with the passage corresponding to the inception of the poetic text).

The chronicle relates that Alfonso had sent Rodrigo Diaz of Vivar to Seville and Cordoba to collect the tribute that the kings of those cities owed him annually. While Rodrigo was in the presence of Mutamid, king of Seville, Mudaffar of Granada attacked Mutamid's territory with the aid of several Christian noblemen – all Alfonso's vassals – including Count García Ordóñez, in spite of Rodrigo's warning that he would not permit one of his lord's tributaries to be threatened without retaliation. Rodrigo gathered an army of Christians and Arabs, overcame the invaders at Cabra, and held Mudaffar's Christian allies captive for three days. It was on this occasion that he pulled out a piece of García Ordóñez's beard, an affront of which Rodrigo strategically reminds the count during the court scene at Toledo in the poetic text (11. 3283—90).