Composed in a metre called the cuaderna vía, it narrates the deeds of the historical Count of Castile, Fernán González.

In 1960 a fourteenth-century Arab roofing tile was discovered in Merindad de Sotoscueva north of Burgos that had some verses of the poem scrawled on it in Old Spanish.

The poem reiterates the campaigns of Fernán González against the Moors, his wars against the Kingdom of Navarre, his debates with the King of León, and his protection of San Pedro de Arlanza, where he was eventually buried.

The poem is designed to present Fernán as the legitimate ruler of all Spain and thus justify Castilian supremacy in the poet's own day.

Very little about Fernán González has been conserved in writing and most of the stories about him were transmitted orally, developing into legend in the process.