The Crusader states were a number of mostly 12th- and 13th-century feudal Christian states created by Western European crusaders in Asia Minor, Greece and the Holy Land, and during the Northern Crusades in the eastern Baltic area. The name also refers to other territorial gains (often small and short-lived) made by medieval Christendom against Muslim and pagan adversaries.
The Crusader states in the Levant--the Kingdom of Jerusalem, the Principality of Antioch, the County of Tripoli, and the County of Edessa--were the first examples of "Europe overseas". Between them, they span the period from 1098 to 1291. They are generally known by historians as Outremer, from the French outre-mer ("overseas" in English).Frank French and Latin were used during the Crusades for Western Europeans, distinguishing them from Greeks.
Beginning in the 7th century, following the foundation of the Islamic religion by Muhammad and through the 8th century Muslim Arabs under the Umayyad Caliphate captured Syria, Egypt, Iran, the Levant and North Africa from the Byzantine Empire, and Iberia from the Visigothic Kingdom.
In 750 a bloody coup brought an end to Umayyad rule, leading to the gradual fragmentation of the monolithic Islamic state and the relocation of the political and economic centre of the Islamic world to Iran and Iraq and away from Palestine. By the run up to the crusades at end of the 11th century the age of Islamic territorial expansion was long gone. However, frontier conditions between the Christian and Muslim world remained across the Mediterranean Sea. From the 8th century, in what later became known as the Reconquista, the Christians were campaigning in Spain and Norman adventurers led by Roger de Hauteville, later King Roger I of Sicily, seized Sicily from the Muslims. The 'Holy Land' had been under Arab Muslim control for more than four centuries with fluctuating levels of tolerance, trade, and political relationships between the Muslims and the Christians. Catholic pilgrims had access to sacred sites and Christian residents in Muslim territories were given Dhimmi status, legal rights, and legal protection. Indigenous Christians were allowed to maintain churches, and marriages between faiths were not uncommon.Malcolm Barber, a British scholar of medieval history, indicates that in the Crusader state of the Kingdom of Jerusalem the Holy Sepulchre was added to in the 7th century and rebuilt in 1022, "after a previous collapse". "In 691-2 Caliph Abd al Malik had built a great dome over the rock here, a place sacred to all three great religions".
The Orthodox Christian Byzantine Empire of Constantinople reached a zenith in early 11th century with frontiers stretching East to Iran while in the West controlling Bulgaria and much of southern Italy. However, from this point the arrival of new enemies on all frontiers placed intolerable strains on the resources of the Emipire and the neighbouring Arab Muslim regimes. This made the Byzantines susceptible to the opportunity presented by western military aid from the Papacy for specific campaigns. The situation was a serious threat to the future of the Eastern Orthodox Byzantine Empire. The Emperor sent a plea to the Pope in Rome to send military aid to restore the lost territories to Christian rule. The result was a series of western European military campaigns into the eastern Mediterranean, known as the Crusades. Unfortunately for the Byzantines, the crusaders had no allegiance to the Byzantine Emperor and established their own states in the conquered regions, including the heart of the Byzantine Empire.
After the First Crusade's capture of Jerusalem and victory at Ascalon the majority of the Crusaders considered their pilgrimage complete and returned to Europe. Godfrey of Bouillon was left with only 300 knights and 2,000 infantry to defend the territory won in the Eastern Mediterranean. Only Tancred of the crusader princes remained with the aim of establishing his own lordship. At this point the Franks held only Jerusalem, Antioch and Edessa but not the surrounding country. Jerusalem remained economically sterile despite the advantages of being the centre of administration of church and state and benefiting from streams of pilgrims.
Consolidation in the first half of the 12th-century established four Crusader states:
These states were the first examples of "Europe overseas". They are generally known as outremer, from the French outre-mer ("overseas" in English).
Modern research based on historical geography techniques indicate that the spatial distribution of Muslims and indigenous Christians was more sharply delineated than previously thought. Palestinian Christians lived around Jerusalem and in an arc stretching from Jericho and the Jordan to Hebron in the South. Central Areas appear to be Muslim from the point of the destruction of the Samarian communities in the 6th-century. These communities are now thought to be of nearly equal size, perhaps even in a 50:50 proportion. The Frankish population of the Kingdom of Jerusalem became concentrated in three major cities. By the thirteenth century the population of Tyre probably exceeded 60,000, then came Acre and the capital itself was the smallest of the three numbering between 20,000 to 30,000. At the zenith of the Crusader Kingdoms, the total Latin population of the region reached around 250,000 with the kingdom amounting to about 120,000 and the total combined numbers in Tripoli, Antioch and Edessa being broadly similar.
The "Law of Conquest" supported the seizure of land and property by impecunious Crusaders from the autochthonous population, enabling poor men to become rich and part of a noble class. Although some historians, like Jotischky, question the model once proposed, in which the primary motivation was understood in sociological and economic rather than spiritual terms. The Franks did not distinguish on grounds of religion; the basic division in society was between Frank and non-Frank, rather than between Christian and Muslim. The new Frankish ruling class did not expel the native population, but adopted strict segregation and at no point attempted to integrate it by way of religious conversion. In this way the Crusaders created a colonial noble class that perpetuated itself through an incessant flow of religious pilgrims and settlers keen to take economic advantage.
Records preserved from John of Ibelin (jurist) indicate that the military force of the kingdom was based on a feudal host of about 647 to 675 knights in 1170. Each feudatory would also provide his own armed retainers. This force would be augmented by mercenary serjants and John records 5,025 of these. In times of emergency the King could also call upon a general muster of the population. The historian Joshua Prawer estimates that the military orders could match the fighting strength of the king's army meaning that the total military strength of the kingdom was can be estimated at 1,200 knights and 10,000 serjants. This meant that conquest was possible, but ephemeral because of a lack of the numbers to maintain military domination. This demographic lack of numbers was also a problem defensively as putting an army into the field required the draining of every Crusader castle and city of every able bodied fighting man. In the case of a defeat such as Hittin there remained no one to resist the invaders. Muslim armies lacked cohesion and seldom campaigned beyond a period between sowing and harvest. As a result the Crusaders adopted tactics, that when faced with a superior invading Muslim force, in which they would avoid direct confrontation instead retreating to strongholds and waiting for the Muslim army to disperse. It took generations before the Muslims recognised that the destruction of walled cities and castles would end Crusader rule. This strategic change forced the Crusaders into their ultimately unsuccessful strategy of destroying Egypt in order to gain enough time to improve the Kingdoms demographic weakness 
The key differentiator in status and economic position in the Crusader States was between urban and rural dwellers. There was no Frankish peasant class, this was a role fulfilled by the native peoples. The Franks imposed their own feudal culture on agricultural production which made little difference in the conditions of the rural population. However, the poll tax on non-Muslims was reversed enabling the feudal Lords to raise punitive levels of revenue from the indigenous peoples, whether Muslim, Jewish or Christian. Very few Muslims lived in urban areas except those in servitude, although indigenous Christians could gain legal status and acquire wealth through commerce and industry in towns.
The territorial gains followed distinct ethnic and linguistic entities. The Principality of Antioch, founded in 1098 and ruled by Bohemond, became Norman in character and custom. The Kingdom of Jerusalem, founded in 1099, followed the traditions of northern France. The County of Tripoli, founded in 1104 (although the city of Tripoli itself remained in Muslim control until 1109) by Raymond de Saint-Gilles became Provençal. The County of Edessa, founded in 1098, differed in that although it was ruled by the French Bouillons and Courteneys its largely Armenian and Jacobite native nobility was preserved. These states were the first examples of "Europe overseas". They are generally known by historians as Outremer, from the French outre-mer ("overseas" in English).
Largely based in the ports of Acre and Tyre, Italian, Provençal and Spanish communes provided a significant characteristic of Crusader social stratification and political organisation. Separate from the Frankish nobles or burgesses, the communes were autonomous political entities closely linked to their countries of origin. This gave the inhabitants the ability to monopolise foreign trade and almost all banking and shipping in the Crusader states. Every opportunity to extend trade privileges was taken. One example saw the Venetians receiving one third of Tyre, its territories and exemption from all taxes, after Venice participated in the successful 1124 siege of the city. However, despite all efforts, the two ports were unable to replace Alexandria and Constantinople as the primary centres of commerce in the region. Instead, the communes competed with the Crown and each other to maintain economic advantage. Power derived from the support of the communards' native cities rather than their number, which never reached more than several hundred. Thus by the middle of the 13th century, the rulers of the communes were barely required to recognise the authority of the crusaders and divided Acre into a number of fortified miniature republics.
The Armenian Kingdom of Cilicia had its origins before the Crusades, but was granted the status of a kingdom by Pope Innocent III, and later became fully westernized by the (French) Lusignan dynasty.
During the Third Crusade, the Crusaders founded the Kingdom of Cyprus. Richard I of England conquered Cyprus on his way to the Holy Land. He subsequently sold the island to the Knights Templar who were unable to maintain their hold because of a lack of resources and a rapacious attitude towards the local population which led to a series of popular uprisings. The Templars promptly returned the island to Richard who resold it to the displaced King of Jerusalem Guy of Lusignan in 1192. Guy went on to found a dynasty that lasted until 1489, when the widow of James II The Bastard, Queen Catherine Cornaro, a native of Venice, abdicated her throne in favour of the Republic of Venice, which annexed the island.
For much of its history under the Lusignan Kings, Cyprus was a prosperous Medieval Kingdom, a commercial and trading hub of Western Christendom in the Middle East. The Kingdom's decline began when it became embroiled in the dispute between the Italian Merchant Republics of Genoa and Venice. Indeed, the Kingdom's decline can be traced to a disastrous war with Genoa in 1373-74 which ended with the Genoese occupying the principal port City of Famagusta. Eventually with the help of Venice, the Kingdom recovered Famagusta but by then it was too late and in any event, the Venetians had their own designs on the island. Venetian rule over Cyprus lasted for just over 80 years until 1571, when the Ottoman Empire under Sultan Selim II Sarkhosh invaded and captured the entire island. The battle for Cyprus between Venice and the Ottoman Empire was immortalized by William Shakespeare in his play Othello, most of which is set in the port city of Famagusta on the eastern shores of the island.
These states faced the attacks of the Byzantine Greek successor states of Nicaea and Epirus, as well as Bulgaria. Thessalonica and the Latin Empire were reconquered by the Byzantine Greeks by 1261. Descendants of the Crusaders continued to rule in Athens and the Peloponnesus (Morea) until the 15th century when the area was conquered by the Ottoman Empire.
The art of the Crusader kingdoms was a varying blend of Byzantine and European styles, with some Islamic elements appearing at times. There are various survivals, especially in architecture and monumental sculpture, with a few frescos and mosaics. There are a very few illuminated manuscripts, most notably the royal Melisende Psalter of c. 1135, now in the British Museum.
The major work of literature surviving from the kingdoms is the Latin chronicle of William of Tyre (c. 1130-1186), Historia rerum in partibus transmarinis gestarum ("History of Deeds Done Beyond the Sea") or Historia Ierosolimitana ("History of Jerusalem"); his other books are lost. He was archbishop of Tyre and an important politician in the Kingdom of Jerusalem, before losing favour and devoting himself to his see and his writing. The chronicle, which is regarded by historians as the most useful source for his period, was soon translated in French and other languages.
Of the enormous literature which the crusades inspired in Europe, only one poem of any importance was actually written in the Holy Land: the so-called Chanson des Chetifs, produced at Antioch a little before 1149.
The emblem used on the seals of the rulers of Jerusalem during the 12th century was a simplified depiction of the city itself, showing the tower of David between the Dome of the Rock and the Holy Sepulchre, surrounded by the city walls. The coins minted in Jerusalem during the 12th century show patriarchal crosses with various modifications. Coins minted under Henry I (r. 1192–1197) show a cross with four dots in the four quarters, but the Jerusalem cross proper appears only on a coin minted under John II (r. 1284/5).
In the Baltic region, the indigenous tribes in the Middle Ages at first staunchly refused Christianity. In 1193, Pope Celestine III urged Christians to have a crusade against the heathens which included the Old Prussians, the Lithuanians and other tribes inhabiting Estonia, Latvia and East Prussia. This period of warfare is called the Northern Crusades.