The fragment of an epic version of La Chanson de Roland, entitled Roncesvalles (ca. 1150), preserved for us in only two folios of a hundred verses, besides being the second oldest epic monument of Spanish literature, shows a distinct Latinity. It first met the gaze of the scholarly world in 1917, when in the Revista de filología española 4.105–204, Menéndez Pidal published the original text as found in the archives of Pamplona together with his own reconstruction and editorial comments. The date of the MS is about 1310 and the original poem appears to have been composed about the middle of the twelfth century. The language is Castilian with light traces of the Navarro-Aragonese dialect.
A Mon, study studied this question.