Crusader states

The Latin Christian polities established in the eastern Mediterranean during the Crusades, chiefly the Kingdom of Jerusalem, County of Edessa, Principality of Antioch, and County of Tripoli.

Kingdom of Jerusalem: A Latin Christian kingdom founded after the First Crusade, centered on Jerusalem and later governed from Acre. The largest and most politically influential crusader state anchored the southern Levant.
Crusader castles: Fortifications built or adapted by crusaders to defend territory and control strategic routes. Castles secured vulnerable frontiers and key roads with limited forces.
First Crusade: The expedition launched in 1096 that captured Jerusalem in 1099 and established Latin rule in parts of the Levant. Its conquests created the first enduring Latin polities in the region.
Siege of Acre (1291): The Mamluk siege that captured Acre, the principal remaining mainland stronghold of the Kingdom of Jerusalem, in 1291. Its fall ended major Latin territorial rule on the Levantine mainland.
Seljuk Empire: A Sunni Muslim empire ruled by the Seljuk dynasty across parts of western and central Asia from the eleventh century. Seljuk powers contested territory and routes with the early crusader states.
County of Edessa: A crusader county founded in northern Mesopotamia in 1098 and conquered by Zengi in 1144. Its fall became a major impetus for the Second Crusade.
Military orders: Religious institutions whose members combined vows of religious life with military service. The Templars and Hospitallers supplied disciplined troops and defended strongholds.
Siege of Jerusalem (1099): The First Crusade's siege and capture of Jerusalem in July 1099. The city's capture enabled the establishment of the Kingdom of Jerusalem.
Second Crusade: A crusading expedition launched in 1147 in response to the fall of the County of Edessa. The county's loss drew western rulers back into eastern Mediterranean conflict.
Zengid dynasty: A Muslim dynasty that ruled parts of Syria and northern Mesopotamia in the twelfth century. Zengi's conquest of Edessa marked a major reversal for the Latin states.

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