At the westernmost tip of this middle Ebro stretch a Romance variant was developed in La Rioja, recorded in the Glosas Emilianenses dating from roughly 1000 AD.

[5] However, political events were going to tip the scale in favour of an increasing assimilation to Spanish in the following centuries, especially after the disputed region was annexed to Castile in 1177 at the expense of Navarre.

Another focal point for the emergence and expansion of Romance in High Aragon and eastern border of Navarre was the ancient Roman road and Way of St. James crossing the Pyrenees to the south from Gascony and extending west via Jaca through the Corridor of Berdún, while the territory was largely Basque-Romance bilingual in 1349.

[6] However, early Navarro-Aragonese speaking communities may have ebbed and become assimilated in some spots on the strength of a predominant Basque-speaking population (overwhelmingly so in Navarre) north away from the Ebro plains, due to demographic, economic and political shifts, e.g. the eastern borders of Navarre in Leire, Sangüesa, Liédena, Romanzado altogether, were densely Basque-speaking in mid and late 16th century.

Navarro-Aragonese was chosen in the High Middle Ages by the Navarrese aristocracy and royal institutions for official records and documents in the 14th century,[8] when Occitan variants fell into disuse after the last devastating war among boroughs in Pamplona, dubbing it ydiomate navarre terrae or lengoage de Navarra (as opposed to the lingua navarrorum, the Basque language).