Glosas Emilianenses

).  He wrote about a thousand years ago in three languages:
* A simplified version of Latin
* The medieval form of a Hispanic Romance language (traditionally regarded as Castilian or Old Spanish, but most probably old Aragonese or a related dialect);
* BasqueThe latter two would have been the vernacular languages in the region surrounding the monastery, although there is a possibility that the author of the glosses was an incomer to the area [The vernacular language in the region is now Castilian Spanish, but there are still some Basque place-names, eg Ezcaray.] . The codex is known as "Aemilianensis 60" ("Aemilianus" is Latin for Emilian, "Millán" or "Emiliano" in modern Spanish) and was preserved in the monastery library at Yuso (the lower re-foundation of the monastery) before being moved to its current location in the Real Academia de la Historia in Madrid. 

Basque Glosses

: these appear to predate all codices, and would thus invalidate the claim of the glosses to be the  "first phrases in the Basque language" (see the photo of a plaque at San Millán de la Cogolla which made this claim in the 1970s).

Only two of the glosses  in "Aemilianensis 60" (of a total of about one thousand) are actually in Basque [ [http://www.vallenajerilla.com/berceo/nietoviguera/glosasvascuences.htm es icon "Glosas en vascuence"] article on Basque glosses] . However, it has been suggested that some of the Romance glosses reflect the influence of the Basque language, the implication being that their author was a fluent Basque-speaker.

Romance Glosses

, which happens to be classified along with Aragonese in a Pyrenean-Mozarabic group.

However the Romance language of the glosses should be classified, they were important in the designation of San Millán de la Cogolla as a World Heritage Site ("cultural" type).

Reference