Spirituals are a genre of songs originating in the USA and created by African Americans. Spirituals were originally an oral tradition that shared Christian values while also describing the hardships of slavery. Although spirituals were originally unaccompanied monophonic (unison) songs, they developed into harmonised choral arrangements over time.
The Fisk Jubilee Singers are an African-American a cappella ensemble, consisting of students at Fisk University. Vocal performances without instrumental accompaniment are called a cappella. The first group was organised in 1871 to tour and raise funds for the college. “Swing Low, Sweet Chariot” is an another famous spiritual. The earliest known recording of this spiritual was in 1909.
Hayes Music blog 