[4] It is the common ancestor of modern Portuguese, Galician, and Fala varieties, all of which maintain a very high level of mutual intelligibility.

[citation needed] The term "Galician–Portuguese" also designates the subdivision of the modern West Iberian group of Romance languages.

[5][6] Gallaecian and Lusitanian influences were absorbed into the local Vulgar Latin dialect, which can be detected in some Galician–Portuguese words as well as in placenames of Celtic and Iberian origin.

[7][8] In general, the more cultivated variety of Latin spoken by the Hispano-Roman elites in Roman Hispania had a peculiar regional accent, referred to as Hispano ore and agrestius pronuntians.

[10] The first known phonetic changes in Vulgar Latin, which began the evolution to Galician–Portuguese, took place during the rule of the Germanic groups, the Suebi (411–585) and Visigoths (585–711).

The nasal vowels would thus be a phonologic characteristic of the Vulgar Latin spoken in Roman Gallaecia, but they are not attested in writing until after the 6th and 7th centuries.

[14] The oldest known document to contain Galician–Portuguese words found in northern Portugal is called the Doação à Igreja de Sozello and dated to 870 but otherwise composed in Late/Medieval Latin.

[18] The Pacto dos irmãos Pais, discovered in 1999 (and possibly dating from before 1173), has been said to be even older, but despite the enthusiasm of some scholars, it has been shown that the documents are not really written in Galician–Portuguese but are in fact a mixture of Late Latin and Galician–Portuguese phonology, morphology and syntax.

In Galicia the oldest document showing traces of the underlying Romance language is a royal charter by king Silo of Asturias, dated to 775: it uses substrate words as arrogio and lagena, now arroio 'stream' and laxe 'stone', and presents also the elision of unstressed vowels and the lenition of plosive consonants;[20] actually, many Galician Latin charters written during the Middle Ages show interferences of the local Galician–Portuguese contemporary language.

Further north, the cities of Lugo, A Coruña and the great medieval centre of Santiago de Compostela remained within Galicia.

Because until comparatively recently, most Galicians lived in many small towns and villages in a relatively remote and mountainous land, the language changed very slowly and was only very slightly influenced from outside the region.

The Fala language, spoken in a small region of the Spanish autonomous community of Extremadura, underwent a similar development to Galician.

Proençaes soen mui ben trobar e dizen eles que é con amor, mays os que troban no tempo da frol e non-en outro, sei eu ben que non an tan gran coita no seu coraçon qual m' eu por mha senhor vejo levar Provençal [poets] tend to compose very well and they say it is out of love, but those who compose when flowers bloom and at no other time, I know well that they don't have in their hearts so great a yearning as I must carry for my Lady in mine.

In Galicia, it is spoken in Entrimo and Lobios and in northern Portugal in Terras de Bouro (lands of the Buri) and Castro Laboreiro including the mountain town (county seat) of Soajo and surrounding villages.

[26] About the Galician–Portuguese languages About Galician–Portuguese culture Manuscripts containing Galician–Portuguese ('secular') lyric (cited from Cohen 2003 [see below under critical editions]): Manuscripts containing the Cantigas de Santa Maria: Critical editions of individual genres of Galician–Portuguese poetry (note that the cantigas d'amor are split between Michaëlis 1904 and Nunes 1932): On the biography and chronology of the poets and the courts they frequented, the relation of these matters to the internal structure of the manuscript tradition, and myriad relevant questions in the field, please see: For Galician–Portuguese prose, the reader might begin with: There is no up-to-date historical grammar of medieval Galician–Portuguese.