Between the 8th and 13th centuries, however, the Carolingian chant commissioned by Charlemagne developed into what we now know as Gregorian chant, which began to influence and eventually replace most of the other Western plainchant traditions. By the 12th century, the Mozarabic, Gallican, Celtic, Old Roman, and Beneventan chant traditions had all been effectively superseded by Gregorian chant.
Between the 8th and 13th centuries, however, the Carolingian chant commissioned by Charlemagne transformed into what we now call Gregorian chant, which began to impact and eventually replace most of the other Western plainchant traditions. By the 12th century, all five Mozarabic, Gallican, Celtic, Old Roman, and Beneventan chant traditions had been effectively replaced by Gregorian chant.