Answer:
The Treaty of Verdun "divided the Carolingian Empire into three parts".
Explanation:
The Treaty of Verdun divided the empire which was built by Charlemagne into 3 portions. These 3 portions was ruled by Charlemagne's three living grandsons. It was considered as a significant because it not only stated the beginning of the empire's dissolution, it gave out the general boundaries of what could individually become nation-states of Europe.
Under the terms of treaty of Verdan, Lothair was permitted to have the emperor title , but he doesn't had any real authority over his brothers. He took the central part of empire including parts Belgium and Netherlands, western Germany, some of eastern part France, a substantial portion of Italy and most of Switzerland. Charles had the western part of empire, which had most of France,and Louis was given the eastern part, which consisted the most part of Germany.