The community structure of the composer-composer network. The five largest composer communities identified using the Louvain method  (covering 6.2% of the composers who account for 60.1% of degrees) correspond well to the established period definitions in classical music history and musicological literatures. For each community we list its size and the major represented period(s). Communities 1A and 1B are subcommunities of Community 1, and correspond to the earlier and the later periods of Medieval and Classical. Community 2 represents the Romantic period, and Communities 3, 4, and 5 represent Modern composers. A closer inspection further differentiates the Modern communities: Community 3 represents US Jazz and Broadway composers, while Community 4 represents the other Modern US composers. Community 5 represents the non-US branch of Modern music.