The first factor was the system of hereditary rulership. Louis the Pious had three sons who eventually rebelled against him and divided up empire in 832. The sons fought against each other, eventually dividing the empire among Charles the Bald (western area), Louis the German (territory east of the Rhine), and Lothair (middle area). These three descendants continued to fight with each other. Charles and Louis split up Lothair’s kingdom after Lothair’s death. After Charles the Bald died, there was a period with several different people contending for the crown which was eventually seized by Charles the Fat. Arnulf, an illegitimate grandson, eventually overthrew Charles the Fat, ending the legitimate Carolingian dynasty. Internal rebellions and Arab and Viking external enemies also weakened the empire.