The Crusades were an important event in medieval European history, taking place from the late 11th century to the early 13th century. It was a series of military campaigns launched by European religious states to recapture holy sites controlled by Islamists, especially Jerusalem. These military campaigns were supported by the Roman Catholic Church and were given the character of religious wars. The background of the Crusades can be understood in several ways. First of all, the Holy Land is of great religious importance to the Christians, and the fall of places like Jerusalem is seen as an insult and a challenge. Secondly, at that time, the ** Church in Europe was undergoing a series of reforms, trying to consolidate the power of the Church through the Eastern Crusade and regain the lost territories. In addition, the feudal lords and knights of various European countries also saw the opportunity of the crusade to the east, hoping to expand their territory and wealth through conquest. At the same time, some merchant and city-states, such as Venice and Genoa, also hoped to control commerce in the eastern Mediterranean through their crusades.
The Crusades were fought eight times, each time consisting of a different leader and army. The First Crusade began in 1096 and lasted until 1099, during which the Crusaders occupied Jerusalem and established the Kingdom of Jerusalem and several minor dependent states. However, these territories were not maintained for long, and the subsequent crusades did not lead to decisive victories. By the 13th century, the Crusades gradually lost their momentum and significance, and finally ended in 1291. The Crusades had a profound impact on European and world history. It not only changed the political landscape of the Middle East, but also had an impact on the social, economic, and cultural aspects of Europe. At the same time, the Eastern Crusade also deepened the hostile relationship between the ** religion and Islam, and had an impact on the spread and development of both religions.
Crusaders did not belong to a particular empire. The Crusades involved knights and soldiers from France, Germany, Italy, and other places, and their armies were collectively known as the Crusaders. During the Crusades, these knights and soldiers from different regions did not form a unified empire, but fought as separate military groups. In the course of the Crusades, there were several actions against the Byzantine Empire, such as the Fourth Crusade, when the Crusaders captured Constantinople, the capital of the Byzantine Empire, and established the Latin Empire on its ruins. But this Latin Empire was not the birthplace of the Crusades, but a product of the Crusades.
To sum up, the Crusaders did not belong to a particular empire, but rather a number of independent military groups made up of knights and soldiers from different parts of Western Europe.