Western classical music has been seen as an art form adhering to universal conventions and rules in a consistent semiotic system, allowing for creative interpretation and individual style, but appreciated by, and comprehensible to, all composers and listeners regardless of their ethnic backgrounds. Local tunes and demotic melodies were not completely absent from the canon of Western art music, but they were mainly present in dance music. Before the mid-18th century, modern church music, chamber music, and opera were not significantly affected by musical vernaculars; but by the late 18th century composers were beginning to take an interest in folk music and sought inspiration in the musical traditions of the peripheries. This process ran concurrently with the general antiquarian interest in folk culture of the late Enlightenment and led to the emergence of national styles in the classical music of the Romantic period, and articulated the differentiated categories of  “art music” (or “classical music”) and “folk music.” The term “genre” played into these distinctions and was initially linked to the functionality of the musical setting (church, opera, domestic space, ballroom). What came later to be considered “folk” or popular music – broadsides, chapbooks, ballads – was part of a shared general repertoire throughout the 18th century, also drawn on by professional composers.

Around 1790 the rise of nationalism valorized the notion of origins. An anonymous provenance and communal authorship of tunes was appreciated as a national value; collective identity shifted from religious or geographical identification towards a shared ownership claim to a certain cultural heritage. This cultural essentialism was more problematic in the case of music than in the case of verbal culture (literary texts) because music was not divided or defined by language borders: the same tune could circulate (with different lyrics) among various ethnic communities. This insight was explicitly recognized in the early-20th-century ethnomusicological research of Béla Bartók (1881–1945). However, his demonstration that there was no such thing as musical purity, and that most folk music or national music incorporates mixed origins, had to subvert an entire century of national essentialism dominating the discourse about, and the production of, music.

In the Romantic century, music was regarded as the true expression of a nation’s character. But the national styles, each claiming to be the reflection of an authentic and distinct national-cultural tradition, were mostly created in the metropolitan capitals of Europe, and the compositions circulated between them. “Scotch tunes” were written by eminent English composers, and melodies in “style hongrois” were published by famous Austrian musicians, far removed from the locations and performative practices where these compositions were said to originate. However, once they gained fame, these tunes were re-adopted in their regions of putative provenance, where a public eager to boast of its musical heritage embraced them as their own. Although this nationalized musical material was neither authentic nor pristine, it stimulated national sentiment. Thus three processes interacted: the adoption of the local colour of rustic peripheries as an inspiring enrichment and a national validator of the classical tradition; a re-acculturation in the peripheries and validation of these styles as authentic; and an ambient discourse identifying the true characteristics of national music, often as part of a wider discursive preoccupation with cultural identity and nationhood.

National music can intensify into nationalist music if it is focused in the nation’s or homeland’s borders and mobilizes its audience for the interests of the nation’s territory and heritage. While nationalist music is directly concerned with the social and political issues of the present, national music invokes a cultural past and identity, aiming to express the “national character”, often gleaned from (idealized) folk traditions.

Like a national language, national music could be invoked to map and draw the proper borders of a nation, to instil nationalist ideas into the minds and hearts of the inhabitants of a land, or to create a basis of emotional identification with the nation. The discovery and cultivation of national music in 19th-century Europe coincided with the rise of Romanticism and Romantic Nationalism. When, by the mid-century, the curiosity and passion for national culture, folklore, and history assumed an increasingly obvious political character, music followed this trend. It became a symbol of national identity, and musical practice became intertwined with the politics of culture. Thanks to the popularity of music and musical practices, the easy diffusion of compositions as printed scores and sheet music, and the immediate co-presence of enthused audiences during performances, nationalist emotions and ideas could spread at an unprecedented speed and effectiveness, rapidly covering a large social and geographic range. Music was a social medium, and a major factor in the creation of a national public sphere.

National music dominated musical production roughly from the 1820s to the 1940s. Composers celebrating the unique individualities of their nations created “national schools”, and were often canonized into cultural icons of their nations. Liszt, Smetana, Glinka, Enescu, and Sibelius all hold special places in the pantheons of their nations, performed though they were in concert halls everywhere. However, it was not unusual for composers to take an interest in the musical vernaculars and demotic styles of nations other than their own: Haydn wrote “Scottish melodies,” Beethoven composed Irish songs, Brahms published “Hungarian dances,” and Rimskij-Korsakov, Debussy, and Ravel created “Spanish” pieces. Along with this transnational interest, composers also served the musical tastes of a growing number of middle-class audiences for whom folk tunes and music with a national inflection carried a political meaning, especially where public life was largely defined by a national struggle for independence and statehood – witness the case of Franz Liszt, who received a sword from his Hungarian admirers in the hope that he would fight for the Hungarian cause. Another such emblematic event was recorded in a letter from Hector Berlioz to one of his friends, describing the emotional outburst of Hungarian concert-goers when they recognized the tunes of the Rákoczi March in Berlioz’s “The damnation of Faust”.

The national element in symphonic music was often represented by a “programme” that proclaimed in the title the music’s embeddedness in history, geography, and cultural traditions. Liszt’s Hungarian rhapsodies, Finlandia by Sibelius, or Cataluña or Iberia by Albéniz aim to establish a musical topography for their nation. This trend went hand in hand with the inclusion of folk tunes and vernacular dances in the texture of classical symphonies. Musical forms such as the verbunkos, mazurka, polonaise, tarantella, or jota were frequently employed, not only as incidental local-colour decorations, but as the very authenticators of the compositions. Most of these dances were by this time associated with specific locations and cultural communities, and adopted as quintessentially national. In one salient case, a crossover was effected: the “Gypsy” music practised by Roma musicians was associated with a Hungarian style and elevated artistic status by Liszt in his book-length essay Des bohémiens et de leur musique en Hongrie (1859). Liszt’s treatise merged contemporary knowledge of the history of the Roma with a Romantic concept of artistic freedom exemplified by the wandering Gypsy musician. Des bohémiens was written to justify an epic conception of Liszt for his Hungarian rhapsodies: a heroic-collective articulation of the national character and the historical role of the Roma, not only in Hungarian society, but in Europe more generally. At the same time the ethnotype of the wandering, socially marginal, freely creative bohémien-gypsy associated the Roma with the sociotype of the nonconformist, Romantic artists and their bohemian lifestyle.

Opera became both a stronghold of national music and a theatre of national emotions in which music served to create and enhance political nationalism. The combination of demotic music, national-historicist libretti in vernacular languages, and stylized and spectacular stage design contributed to the extraordinary effect of these national operas. Operas became amplifiers and active agents of nationalism. Crowds gathered in the opera, sympathized with the emotions presented on the stage, transposed them into their own lives, and disseminated the politicized message by repeating their favourite songs and choruses in various contexts outside the opera house. People did not launch a revolution after reading a poem or a novel, but some uprisings actually did begin in theatres and opera houses. The Belgian revolution of independence in 1830 was triggered by a performance of Auber’s La muette de Portici in Brussels. In 1843, after the first hugely successful performance of Verdi’s I Lombardi in Milan, the chorus “O Signore, dal tetto natio” was immediately adopted as a patriotic anthem, like the chorus “Va pensiero” from his Nabucco a year earlier. Even if it was not the stated intention of the composer that a certain opera be read as nationally symbolic, the solidarity of the audiences could interpret it as an act of political performativity. Operas gained popularity both inside and outside the theatre: arias and choruses were sung at public gatherings and protest marches, and operatic heroes, regarded as role models, could inspire fashion trends.

Operas could appeal to the general public because the gap between stage and audience was constantly diminishing. Operas were being staged in public venues accessible to all paying members of the public. Instead of mythological figures (Orpheo), monarchs (L’incoronazione di Poppea), or aristocrats (Don Giovanni), 19th-century operas presented the lives of common people suffering from aristocratic or royal oppression (Fidelio) or of entire nations suffering from tyranny (Guillaume Tell, Don Carlo, Nabucco). The libretti, the musical texture, and the settings also played a vital role in popularizing opera all over Europe. While the language of the libretti had traditionally been either Italian or French, or more rarely German, the 19th century saw the rise of libretti in vernacular languages like Croatian, Czech, Danish, Greek, Hungarian, Polish, Romanian, Serbian, or Swedish. The music drew intentionally on local folk songs or dances that also enhanced the spirit of the public, who recognized their everyday rites and entertainments presented on the stage as "high art". The settings of the plots were deliberately folkish (couleur locale), imitating village life, reflecting the local culture and rustic nostalgia of the public. All these factors contributed to bridging the gap between the stage and the audience, between high culture and low culture, between people’s lives and artistic representations of their everyday reality.

However, opera was more than merely a representation of socio-political reality; it functioned as an active agent for influencing the social and political atmosphere of the time. In the opera houses, individual listeners were turned into an “embodied community” (Ann Rigney’s term). Public opera performances galvanized the sense of belonging to the same performative community, or what Benedict Anderson called the “unisonality” of collective audiences. Especially the chorus (understood as the voice of the people) played a major role in uniting stage action and audience sentiment.

The music of the opera chorus was disseminated through the mushrooming choral societies throughout Europe. More than leisure-time associations with a shared cultural interest and musical appreciation, they became platforms for informal social, and also national, middle-class self-organization. The choral repertoire, while including a variety of genres (not all of them nationalist), contained enough material to transform singing societies into pioneers of musical nationalism, translating the cultural production of the opera houses and concert halls into national mass mobilization.