Galician is a Romance language. It was formed against the end of the 8th century from a Celtic substratum and the Germanic superstrata (Swebians, Visigoths) based on Latin. In the lexicon there were samples, currently alive, of languages prior to the arrival of the Romans. For example, carqueixa, queiruga, touza, labio, me lo para, lágrima, turbot… In toponymy we have numerous examples: Viascón, Bergantiños, O Grove… or in the names of rivers: Sar, Navia, Landro…
The medieval period (X-XV) was bright for Galicia thanks to the religious, noble and cultural power. The codices with the Galician medieval lyric, the collections of legal documents or texts written by monarchs, such as Rei Afonso X El Sabio, author of the “Cantigas de loor de Santa María”, remain as testimonies.
Due to socio-political vicissitudes (independence of southern Galicia, which gave rise to Portugal; civil wars; irmandiñas revolts; intervention of the Catholic Monarchs…) Galician was losing its status in favor of Castilian, which immediately became the only language in writing despite the fact that the population spoke Galician.
Over the years there was also a sociolinguistic change since the decent classes adopted Castilian as a brand against Galician, identified with the lower classes. Added to this was a policy of expelling Galician from the documentation, of Castilianizing toponymy (Sanjenjo, Rianjo, Mugía…) or even modifying surnames (Otero for Outeiro, Seijas for Seixas, Molinos for Muíños…).
Galician was always maintained as an oral language. Slowly, voices arose that claimed his dignity (Count of Gondomar, Father Feijóo, Fray Martín Sarmiento…). It will be with the Rexurdimento (S. XIX) when a continuous process of recovery in writing begins.