In The Quest for El Cid, Richard Fletcher has created a biographical history that portrays an era primarily through focusing on one individual. The biographical aspect of the book is often fragmentary, in part because so little factual information is known about Rodrigo Diaz, the person who became known as El Cid. However, the rich panorama of the epoch more than compensates for the limited historical information concerning Diaz's life story.

Fletcher devotes a chapter to the historical sources he used, noting that they are severely limited for the eleventh century. Only in certain parts of Spain, for example, was a type of epic "public poetry" fully developed. This tradition of poetry, primary used in Catalonia, would eventually generate El Cantar de mio Cid, or The Poem of My Cid:

The earliest literary composition devoted to the exploits of Rodrigo Diaz is a poem of this type. Now in the Bibliotheque Nationale in Paris, it has come down to us in a manuscript which was brought from Catalonia to Paris in the seventeenth century. The manuscript had been copied at Ripoli [a monastery] about the year 1200.

The author takes lines from The Poem of My Cid that describe features of the time, some of which are still extant today and others that are gone, encouraging the reader to imagine themselves in that exact setting. For example, after Diaz conquered Valencia, he flew his flag atop the fortress. A modern visitor can climb a newer bell tower on the same fortress and, if they ignore the sprawl of the modern city, admire the rich agricultural lands as Diaz might have done:

How the conquerors from bleak Castile must have gasped as they looked upon the ordered yield of that astonishingly abundant landscape, the paddy-fields of rice, the lustrous citrus groves . . . the vineyards, olive groves, and cornfields. . . . [At the city’s former central crossroads] the principal mosque, which Rodrigo converted into a church . . . . underlay the existing cathedral.

Fletcher notes that earlier synthetic historical treatments, especially those written in times of intense Spanish nationalism, emphasized Diaz’s role in fighting against the Moorish rulers of Spain. However, Fletcher states that his historical record, which includes Diaz’s less consistent allegiances (Diaz also fought with the Moors against Spain), is less popular in Spain but is more factually accurate. In particular, he cites Ramón Menéndez Pidal’s now-classic 1929 work, La España del Cid, claiming that he both owes a debt to and departs from this text. Fletcher explains that, to some extent, this work:

is a tract for [Pidal's] own times disguised as history. . . . A patriot whose native land was going through troubled times, [Pidal] presented his countrymen with a national hero in whom they could rejoice and to whose virtues they should aspire. . . . He wrote at a time . . . when Spanish historians were preoccupied with identifying and delineating the essence or soul of Spanishness.

In Fletcher's largely contrasting historical view, rather than tracing one historical line chronologically, Fletcher's historical account situates the then nascent Spain within the complex European and Middle Eastern geopolitical landscape of the time.