The litany is a series of invocations for deliverance and intercession usually addressed to the Trinity, the Virgin, angels, apostles, martyrs, confessors, and virgins, individually and as groups. Such litanies are encountered in the East from the third century and the West from the late fifth century. The saints included in a litany varied according to region and patronage. For this reason, they often yield valuable evidence concerning the origin of a manuscript. Litanies of saints increased in length throughout the Middle Ages. See also Suffrage.