Its name was derived from the Germanic Angrivarii (Latin: Angarii) tribe which had joined the Saxon tribal confederation, and it was centered on the town of Minden, see of a bishopric since 803. The Angrivarii lands were conquered by Charlemagne during the Saxon Wars; according to the Royal Frankish Annals, the Angrian commanders concluded a separate peace agreement with the Carolingian Empire near Bückeburg in 775.
Upon the expansion of the Kingdom of Prussia towards the old Saxon regions (initially in 1815, and again in 1866), the title Duke of Angria (German: Herzog von Engern) was revived and included into the extended Prussian royal titles, and later (1871) into the extended titles of German Emperors from the House of Hohenzollern.