The Frankish Empire, also known as the Merovingian Empire, the Holy Roman Empire, and Francia, was a vast empire. It conquered Gaul and Italy eventually. The massive empire grew in strength rapidly, repelling Islamic Vikings and Slavs. When Islam rose, the Franks resisted the onslaught and, to this day, most of Western Europe is Christian thanks to the Franks. However, the empire eventually collapsed due to too much trust put into local leaders.