Why did a new dynasty come to power in the Frankish state?

In 481, the first Frankish kingdom was created, and Clovis, the founder of the Merovingian dynasty, became its ruler. In 751, Pepin the Short was able to seize power and remove the last member of the Merovingian dynasty. So the Carolingians began to rule in France. Pepin III finally managed to unite the scattered lands of France and create a single state. The work of his father was continued by Charlemagne, who managed to create a huge state in the center of Europe.