Apparently the chant was unknown in Rome before about AD 1000, and may have originated in the Gallican liturgy.
In modern chantbooks, the music given for the chant is exactly the same as for the Ite missa est, but it is not known how much that was true in the medieval period as well.
Martial and Notre Dame schools of polyphony, including a dozen settings in the Magnus Liber Organi.
By 1963, it was only recited or chanted when an exposition immediately follows the Mass (Eucharisticum Mysterium, 120).
It is rarely heard in Anglo-Saxon countries, processions being rarities there.