Can you send me more infos about the referralls?

In the 11th century, the Seljuk Turks took over much of the Middle East, occupying Persia during the 1040s, Armenia in the 1060s, and Jerusalem in 1070. In 1071, the Turkish army defeated the Byzantine army at the Battle of Manzikert and captured the Byzantine Emperor Romanus IV (r. 1068–71). The Turks were then free to invade Asia Minor, which dealt a dangerous blow to the Byzantine Empire by seizing a large part of its population and its economic heartland. Although the Byzantines regrouped and recovered somewhat, they never fully regained Asia Minor and were often on the defensive. The Turks also had difficulties, losing control of Jerusalem to the Fatimids of Egypt and suffering from a series of internal civil wars.[206] The Byzantines also faced a revived Bulgaria, which in the late 12th and 13th centuries spread throughout the Balkans.[207]

The crusades were intended to seize Jerusalem from Muslim control. The First Crusade was proclaimed by Pope Urban II (pope 1088–99) at the Council of Clermont in 1095 in response to a request from the Byzantine Emperor Alexios I Komnenos (r. 1081–1118) for aid against further Muslim advances. Urban promised indulgence to anyone who took part. Tens of thousands of people from all levels of society mobilised across Europe and captured Jerusalem in 1099.[208] One feature of the crusades was the pogroms against local Jews that often took place as the crusaders left their countries for the East. These were especially brutal during the First Crusade,[77] when the Jewish communities in Cologne, Mainz, and Worms were destroyed, and other communities in cities between the rivers Seine and Rhine suffered destruction.[209] Another outgrowth of the crusades was the foundation of a new type of monastic order, the military orders of the Templars and Hospitallers, which fused monastic life with military service.[210]

The crusaders consolidated their conquests into crusader states. During the 12th and 13th centuries, there were a series of conflicts between those states and the surrounding Islamic states. Appeals from those states to the papacy led to further crusades,[208] such as the Third Crusade, called to try to regain Jerusalem, which had been captured by Saladin (d. 1193) in 1187.[211][Y] In 1203, the Fourth Crusade was diverted from the Holy Land to Constantinople, and captured the city in 1204, setting up a Latin Empire of Constantinople[213] and greatly weakening the Byzantine Empire. The Byzantines recaptured the city in 1261, but never regained their former strength.[214] By 1291 all the crusader states had been captured or forced from the mainland, although a titular Kingdom of Jerusalem survived on the island of Cyprus for several years afterwards.