What and when was the Treaty of Verdun? How did the division of Charlemagne’s kingdom among his grandsons affect changes in the once-unified empire?

The Treaty of Verdun, signed in 843, divided the Carolingian Empire among the three sons of Louis I, Charlemagne's son. This treaty broke up the once-unified country among the three sons, who were riven by divisions following their father's death. In this treaty, Lothair I, who was formerly the emperor, received what would become Belgium and the Netherlands, along with northern Italy and some parts of modern-day France. Charles the Bald ruled over what would become the Kingdom of France, while Louis the German took what would become the Kingdom of Germany. The division of the empire among the three surviving grandsons of Charlemagne resulted in fragmentation and a weakening of the once-powerful empire. For example, Lothair's three sons also fought among themselves, causing their kingdom to disintegrate. The Treaty of Verdun brought about the rise of European feudalism, as lords began to fill in the power vacuum caused by the downfall of once-powerful emperors.