Military history of the Crusader states
The Seljuk–Crusader War began when the First Crusade wrested territory from the Seljuk Turks during the Siege of Nicaea in 1097 and lasted until 1128 when Zengi became atabeg of Aleppo. At the latter date, the chief threat to the Crusaders from the east and north became the Zengids. The conflict was generally fought between European Crusaders and the Seljuk Turks and their vassals. The Muslim Syrian emirates occasionally allied themselves with the Christians against rival states.
History of the Jews and the Crusades
Robert Chazan's "In the Year 1096: The First Crusade and the Jews" provides details as to the changes made in Jewish/Christian relations as a result of the First Crusade. He focuses on whether or not the crusades really had a salient impact on the Jews of the time and in the future, pointing out that persecution was nothing new to them, yet also talking about the importance of their being made extremely distinct within the European community by the crusades. They were no longer part of it to any great extent, but rather were made out to be part of the "others" as many in Europe already had been, such as atheists and pagans.