The formation, development and disintegration of the feudal system was the main line of European history during this period.
1. Economy - The economy in the Middle Ages was mainly a feudal manor-style natural economy. A number of commercial cities emerged, forming a trading area centered on the Mediterranean.
2. Cultural ideas - the church controlled secular power, ruled very harshly, and controlled the culture and education of Western Europe. Priests cannot get married, advocate abstinence, promote scholastic philosophies such as the Trinity and original sin, strictly control the spread of scientific ideas, and set up religious inquisitions to punish heretics. School education is also designed to serve theology
3. Politics - - Feudal hierarchical relationships were strict. Feudal lords, large and small, formed a pyramid-like hierarchy, but their rights and obligations were limited. A ducal system of duke-hou-uncle-son-male was established, with dukes below the pope and king, and knights as the lowest level of feudal lords.
4. Military - Medieval wars were composed of loosely organized fighting groups that confronted and clashed with each other on the battlefield that required the use of strategy and mobilization, and then evolved step by step. Part of the evolution is reflected in the development of different arms and weapons, and how to use them. The main features are knights and cold weapons.