Claim: Charlemagne was crowned emperor.

The Carolingian Empire -LRB- 800 -- 888 -RRB- was a large empire in western and central Europe during the early Middle Ages . It was ruled by the Carolingian dynasty , which had ruled as kings of the Franks since 751 and as kings of the Lombards of Italy from 774 . In 800 , the Frankish king Charlemagne was crowned emperor in Rome by Pope Leo III in an effort to revive the Roman Empire in the west during a vacancy in the throne of the eastern Roman Empire . After a civil war -LRB- 840 -- 43 -RRB- following the death of Emperor Louis the Pious , the empire was divided into autonomous kingdoms , with one king still recognised as emperor , but with little authority outside his own kingdom . The unity of the empire and the hereditary right of the Carolingians continued to be acknowledged .   In 884 , Charles the Fat reunited all the kingdoms for the last time , but he died in 888 and the empire immediately split up . With the only remaining legitimate male of the dynasty a child , the nobility elected regional kings from outside the dynasty or , in the case of the eastern kingdom , an illegitimate Carolingian . The illegitimate line continued to rule in the east until 911 , while in the western kingdom the legitimate Carolingian dynasty was restored in 898 and ruled until 987 with an interruption from 922 to 936 .   The size of the empire at its inception was around 1112000 km2 , with a population of between 10 and 20 million people . To the south it bordered the Emirate of Córdoba and , after 824 , the Kingdom of Pamplona ; to the north it bordered the kingdom of the Danes ; to the west it had a short land border with Brittany , which was later reduced to a tributary ; and to the east it had a long border with the Slavs and the Avars , who were defeated and their land incorporated into the empire . In southern Italy , the Carolingians ' claims to authority were disputed by the Byzantines -LRB- eastern Romans -RRB- and the vestiges of the Lombard kingdom in the Principality of Benevento .   Use of the term `` Carolingian Empire '' is a modern convention . The language of official acts in the empire was Latin . The empire was referred to variously as universum regnum -LRB- `` the whole kingdom '' , as opposed to the regional kingdoms -RRB- , Romanorum sive Francorum imperium -LRB- `` empire of the Romans and Franks '' -RRB- , Romanum imperium -LRB- `` Roman empire '' -RRB- or even imperium christianum -LRB- `` Christian empire '' -RRB- .