How did the Franks emerge as the group that would establish the next major territorial empire in the west? What were the stages by which they did so?

First, their war power and attack tactics which, for the medieval perspective, were strong and organized. And second, their alliance with the emergent Christian religion and the Catholic Church. The stages for this presence and dominance in Europe can be sum up into the Merovingian Dynasty, and the Charlemagne Empire.

Explanation:

The first mention to the Franks in the historical literature was in 257 AD, and their strength was known everywhere. Gradually, the Franks were incorporated into the Roman Empire and created their first kingdom lead by Clovis I. He ascended the throne in 481, when he was 15, and consolidated the Merovingian dynasty, which lasted for 200 years. The Franks were pagans when the majority of the barbarian tribes of the time already followed the precepts of Christianity. It was King Clovis I who was responsible for the conversion of the Franks to Christianity. Clovis I's strategy, however, was to facilitate the acceptance of the Welsh and Romans after the conquest of the Eastern Roman Empire. The proximity with Christianism was followed by Charlemagne, who expanded the Franks Kingdom and under his rule, the Franks dominated and traced the European territory.