During the Carolingian Renaissance there was an increase of architecture.
Beginning with Pippin II, the Carolingians set out to put the regnum Francorum ("kingdom of the Franks") back together, after its fragmentation after the death of Dagobert I, a Merovingian king
 The Carolingians had the practice of making their sons minor kings in the various regions (regna) of the Empire, which they would inherit on the death of their father, which Charlemagne and his son Louis the Pious both did for their sons

