Classification and relation with Portuguese
Map showing the historical retreat and expansion of Galician (Galician and Portuguese) within the context of its linguistic neighbors between the year 1000 and 2000
Modern Galician and Portuguese originated from a common medieval ancestor designated variously by modern linguists as Galician-Portuguese (or as Medieval Galician, Medieval Portuguese, Old Galician or Old Portuguese). This common ancestral stage developed from Vulgar Latin in the territories of the old Kingdom of Galicia, Galicia and Northern Portugal, as a Western Romance language. In the 13th century it became a written and cultivated language with two main varieties, but during the 14th century the standards of these varieties, Galician and Portuguese, began to diverge, as Portuguese became the official language of the independent kingdom of Portugal and its chancellery, while Galician was the language of the scriptoria of the lawyers, noblemen and churchmen of the Kingdom of Galicia, then integrated in the crown of Castile and open to influence from Castilian language, culture, and politics. During the 16th century the Galician language stopped being used in legal documentation, becoming de facto an oral language spoken by the vast majority of the Galicians, but having just some minor written use in lyric, theatre and private letters.
It was not until the 18th century that linguists elaborated the first Galician dictionaries, and the language did not recover a proper literature till the 19th century; only since the last quarter of the 20th century is taught in schools and used in lawmaking. The first complete translation of the Bible from the original languages date from 1989. Currently, at the level of rural dialects, Galician form a dialect continuum with Portuguese in the south, and with Astur-Leonese in the east. Mutual intelligibility (estimated at 85% by Robert A. Hall, Jr., 1989) is very high between Galicians and northern Portuguese.
The current linguistic status of Galician with respect to Portuguese is controversial in Galicia, and the issue sometimes carries political overtones. There are linguists who deal with modern Galician and Portuguese as norms or varieties of the same language. Some authors, such as Lindley Cintra, consider that they are still co-dialects of a common language in spite of differences in phonology and vocabulary, while others argue that they have become separate languages due to differences in phonetics and vocabulary usage, and, to a lesser extent, morphology and syntax. Fernández Rei in 1990 stated that the Galician language is, with respect to Portuguese, an ausbau language, a language through elaboration, and not an abstand language, a language through detachment.
With respect to the external and internal perception of this relation, for instance in past editions of the Encyclopædia Britannica, Galician was defined as a Portuguese dialect spoken in northwestern Spain. On the other hand, the director of the Instituto Camões declared in 2019 that Galician and Portuguese were close kin, but different languages. According to the Galician government, universities and main cultural institutions, such as the
Galician Language Institute or the Royal Galician Academy, Galician and Portuguese are independent languages that stemmed from medieval Galician-Portuguese  and modern Galician must be considered an independent Romance language belonging to the group of Ibero-Romance languages having strong ties with Portuguese and its northern dialects. The standard orthography has its roots in the writing of relatively modern Rexurdimento authors, who largely adapted Spanish orthography to the then mostly unwritten language. Most Galician speakers do not regard Galician as a variety of Portuguese, but as a different language, which evolved without interruption and in situ from Latin, both languages maintaining separate literary traditions since the 14th century.
Portuguese Early Modern Era grammars and scholars, at least since Duarte Nunes de Leão in 1606, considered Portuguese and Galician two different languages  derived from old Galician, understood as the language spoken in the Northwest before the establishment of the Kingdom of Portugal in the 12th century. The surge of the two languages would be the result of both the elaboration of Portuguese, through the royal court, its internationalization and its study and culture;
and of the stagnation of Galician
Vindel's parchment, containing music and lyrics of several 13th-century cantigas
by Martin Codax
The earliest internal attestation of the expression Galician language ("lingoajen galego") dates from the 14th century. In Spanish "lenguaje gallego" is already documented in this same century, circa 1330; in Provençal circa 1290, in the Regles de Trobar by Catalan author Jofre de Foixà: "si tu vols far un cantar en frances, no·s tayn que·y mescles proençal ne cicilia ne gallego ne altre lengatge que sia strayn a aquell" [If you want to compose a song in French, you should not admix Provençal nor Sicilian nor Galician nor other language which is different from it].
Reintegrationism and political implications
Private cultural associations, not endorsed by Galician or Portuguese governments, such as the Galician Language Association (Associaçom Galega da Língua) and Galician Academy of the Portuguese Language (Academia Galega da Língua Portuguesa), advocates of the minority Reintegrationist movement, support the idea that differences between Galician and Portuguese speech are not enough to justify considering them as separate languages: Galician would be simply one variety of Galician-Portuguese, along with Brazilian Portuguese; African Portuguese; the Galician-Portuguese still spoken in Spanish Extremadura, Fala; and other dialects. They have adopted slightly-modified or actual Portuguese orthography, which has its roots in medieval Galician-Portuguese poetry as later adapted by the Portuguese Chancellery.
According to Reintegrationists, considering Galician as an independent language reduces contact with Portuguese culture, leaving Galician as a minor language with less capacity to counterbalance the influence of Spanish, the only official language between the 18th century and 1975. On the other hand, viewing Galician as a part of the Lusophony, while not denying its own characteristics (cf. Swiss German), shifts cultural influence from the Spanish domain to the Portuguese. Although it is difficult to clarify the political positions of those who favor one view or the other, Reintegrationism is usually associated with the more radical spectrum of Galician independentism . Some scholars have described the situation as properly a continuum, from the Galician variants of Portuguese in one extreme to the Spanish language in the other (which would represent the complete linguistic shift from Galician to Spanish); reintegrationist points of view are closer to the Portuguese extreme, and so-called isolationist ones would be closer to the Spanish one; however, the major Galician nationalist parties, Anova–Nationalist Brotherhood and Galician Nationalist Bloc, do not use reintegrationist orthographical conventions.
Official relations with the Lusophony
The parliament of Galicia approved unanimously in 2014 the law 1/2014 of links with the Lusophony. As a consequence, on 20 October 2016, the city of Santiago de Compostela, the political capital of Galicia, approved by unanimity a proposal to become an observer member of the Union of Portuguese-Speaking Capitals (UCCLA). Also, on 1 November 2016, the Council of Galician Culture (Consello da Cultura Galega) was admitted as a consultative observer of the (CPLP).
A "friendship and cooperation" protocol was signed between the Royal Galician Academy (RAG) and the Brazilian Academy of Letters on 10 January 2019. Víctor F. Freixanes, president of the RAG, stated during the ceremony that "there is a conscience that the Galician language is part of a family which includes our brothers from Portugal, Brasil, Angola, Cape Verde, Mozambique... a territory full of possibilities also for Galician. We always said that Galician is not a regional language, but is in fact part of that international project".