The Ambrosian hymns are a collection of early hymns of the Latin liturgical rites, whose core of four hymns were by Ambrose of Milan in the 4th century.
The hymns of this core were enriched with another eleven to form the Old Hymnal, which spread from the Ambrosian Rite of Milan throughout Lombard Italy, Visigothic Spain, Anglo-Saxon England and the Frankish Empire during the early medieval period (6th to 8th centuries); in this context, therefore, the term “Ambrosian” does not imply authorship by Ambrose himself, to whom only four hymns are attributed with certainty, but includes all Latin hymns composed in the style of the Old Hymnal.
The Frankish Hymnal, and to a lesser extent the “Mozarabic (Spanish) Hymnal” represent a reorganisation of the Old Hymnal undertaken in the 8th century. In the 9th century, the Frankish Hymnal was in turn re-organised and expanded, resulting in the high medieval New Hymnal of the Benedictine order, which spread rapidly throughout Europe in the 10th century, containing on the order of 150 hymns in total.