During the 1000's AD a group of Muslims, the Turks, took over the Holy Land. This group captured many and even threatened the capital city. They almost wiped out regions and left many defenseless. Due to these events, the Christians asked the Pope to help them. The Pope then started the crusades.
The emperor of Constantinople, Alexios 1, was becoming unsure of what to do when the Turks begun defeating them and seizing the Holy Land. It got to the point where the Pope's help was asked for. The Pope then called for a meeting in France to begin the crusades. However, Alexios shipped people away instead of allowing them to enter Constantinople.
People going on crusade wanted to join the in order to regain the Holy Land. They worked together to attempt to defeat the Turks. In this time, the Pope promised that whomever made the journey would have all their sins forgiven and that they would go to heaven.
The peasants crusade begun when the Pope called for the meeting in France. The peasants were then shipped across the Bosporus after being denied to enter Constantinople. When they arrived in the Asia minor, the Peasants were quickly defeated by the Turks.
In 1099 the Crusaders begun the first Crusade to arrive in the Holy Land. The Muslims had been weak and disorganized due to the fighting amongst each other. In July, after a month of fighting, the Crusaders captured Jerusalem and split it into four small kingdoms. This is were they brought in the feudal and manor systems from Europe.
In the Holy Land, the Crusaders built giant stone walls and castles to strengthen their small numbers and control the trading routes.