The term "swing dance" is commonly used to refer either to a group of dances developing during the swing era (late 1920s to 1940s) or to the current dances and dance scenes centred on swing dancing. Historical swing dances as a family are usually situated within an African American vernacular dance tradition, though there are some exceptions which developed within the white or mainstream American community. Almost all of the former feature the syncopated timing associated with African American and West African music and dance, and with jazz dances of the jazz era (late 19th century to the 1940s). Most swing dances developed in response to swing (genre) music, though many of these styles and their descendents are danced today to modern music. There are swing dance scenes in many developed Western and Asian countries throughout the world, though each city and country varies in the popularity of specific dances, local culture and definitions of "swing dance" and "appropriate" dance music.