The Iberian Peninsula is not unusually diverse regarding languages, especially if you compare Spain to countries like France, Germany, and Italy.

So, as of now, Spain has one official national language (Castilian), and its constituent autonomous communities can make any languages official in their territories. That means that on a regional level Galician, Basque, Catalan, and Occitan are also official languages. If things go as planned, we shall soon see Astur-Leonese (also known as Asturian or Bable) become official in the region of Asturias. There is also a recent but minor push to make Cantabrian an official language.

Depending on the definition and catalogation of languages and dialects, in Spain there may be a dozen or so languages+dialects: Galician, Astur-Leonese, Cantabrian, Basque, Aragonese, Catalan, Occitan, Castilian, Castúo, Panocho, etc. This quantity is not that different, especially if one considers population and extension, to the variety there still is in France, despite France's best efforts to crush linguistic diversity. Italy too has a tremendous amount of different languages, although they tend to be called dialects.

In recent times, Italy has become more linguistically unified, with a more standardised version of Italian being spoken by the people, especially the younger generations, which may not speak the "dialects". Philosopher Luciano de Crescenzo once noted that Italian should not be called "the language of Dante", but rather "the language of Pippo Baudo", and not without logic. Pippo Baudo was a famous TV news anchor, and with that massive diffusion he helped in make Italian language more widely available in Italy (paradoxical as this phrase may sound).

France had strong policies of linguistic unification since the late 18th century, in the times of the Revolution. This cannot be explained any better than by the Decrees of Linguistic Terror (Decrees of 2nd Thermidor year II, 27 Brumaire year III, and 10 Prairial year X) that proscribed regional languages, and established prison sentences for any civil servants who used any regional language in any document, even if the document was private in its legal nature. One of the members of the Comité de Salut Public, monsieur Barère de Vieuzac had some truly strong opinions on the matter of regional languages: Federalism and superstition speak Low Breton, emigration and reaction speak German, the enemies of the Republic speak Italian, aand fanaticism speaks Basque. Let us crush this instruments of damnation and error

Spain, on the other hand, never actually had such heavy-handed policies. It is true that during the 18th, 19th and part of the 20th century, the Spanish regional languages were not official, but they were not actively persecuted either. In the 19th century, the time of Romanticism, and the Spring of the Peoples, there was a great effort from regional intellectuals to bring prestige to the regional languages. Thus we finf the Catalan and Valencian Renaixença, the Galician Rexurdimento, and the eclosion of Basque Nationalism, resulting in a torrent of publications in regional languages, and a great deal of interest in the linguistic variety.

In the 20th century, the II Spanish Republic opened the possibility for regional languages to become official at the regional level, but the dream did not last long, as soon another Civil War devastated Spain, and it was followed by a 40-year-long dictatorship.

During Franco's dictatorship, regional languages were not official, but they were not exactly persecuted either. There was a very abundant literary production in Catalan, with plenty of literary prizes since the 1940s, there were private schools that had Basque language as its vehicular one, and a sizeable literary production in Galician since 1950.

With the Transition to democracy and the decentralisation of the Spanish State, regional languages finally gained an official status, and the regional adminsitrations have been doing their utmost to promote those languages: have them be vehicular in all levels of education, make them official, promote any cultural manifestation in the regional languages, have strong regional TV stations that operate in the regional languages, etc.