Set in the Carolingian era, it was written much later. There are nine extant manuscripts of the Song of Roland in Old French. The oldest of these manuscripts is held at the Bodleian Library at Oxford. This copy dates between 1129 and 1165 and was written in Anglo-Norman.
Scholars estimate that the poem was written, possibly by a poet named Turold, between approximately 1040 and 1115, and most of the alterations were performed by about 1098. Some favor an earlier dating, because it allows one to say that the poem was inspired by the Castilian campaigns of the 1030s, and that the poem went on to be a major influence in the First Crusade. Those who prefer a later dating do so on grounds of what they interpret as brief references made in the poem to events of the First Crusade.
In the poem, the term d'oltre mer or l'oltremarin comes up three times in reference to named Muslims who came from oltre mer to fight in Spain and France. Oltre mer, modern French Outremer, literally "oversea, beyond sea, other side of the sea", is a native French term from the classical Latin roots ultra = "beyond" and mare = "sea". The name was commonly used by the Crusaders for Palestine.
The occurrence of this term in the poem cannot be interpreted as showing influence from the Crusades in the poem; on the contrary, the way it is used in the poem, in which it is simply a Muslim land, indicates that the author of the poem was unacquainted with the Crusades, and that the term was in French before the Crusades began meaning the far side of the Mediterranean Sea. The bulk of the poem is adjudged to date from before the Crusades (which started in 1098), but there are a few items where questions remain about these items being late additions shortly after the Crusades started.