Jubilee Quartets started in the mid-1800’s as an outgrowth of the African American university singing movement.

The early a cappella vocal groups were originally known as Jubilee Quartets because of the nature of the repertoire and characteristics of the performance.

They most often consisted of men
and contained heavy influences of both  African American and western practices

[embedyt] https://www.youtube.com/watch?v=ey9z8o7y-7A[/embedyt]

In the context of African American music, a quartet was defined as a vocal ensemble that consisted of minimum four voices and a max of six voices singing four-part harmony arrangements in either an a cappella style or with limited instrumentation