Analysis of information sources in references of the Wikipedia article "ポピュラー音楽" in Japanese language version.
...music of, and since, the 'TIn Pan alley' era, i.e. the 1880s onwards in the USA and the early years of the 20th century in Europe. [] the music that, with the growth of industrialization in the 19th century, began to develop distinctive characteristics in line with the tastes and interests of the expanding urban middle classes.
