Final answer:
During the Renaissance, feudalism and manorialism declined as centralized nation states emerged and the merchant class gained power. The Crusades and social and economic changes played major roles in causing this decline.
Step-by-step explanation:
During the Renaissance, feudalism and manorialism began to decline. Feudalism, the political structure in which knights and lower-status nobles owed military service to their overlords, gradually lost power as centralized nation states emerged. Manorialism, the organization of peasants into villages that owed rent and labor services to the nobles, also weakened as the merchant class gained wealth and power. The two main factors that caused the decline of feudalism and manorialism were the Crusades, which led to the centralization of power, and the social and economic changes brought about by the Great Famine, Black Death, and Hundred Years' War.