Answer:
Turks Seljuks in the 11th Century rose as a great to the Byzantine Empire. They started taking their territories in the region of Asia Minor. Byzantines tried to confront them, but were heavily defeated in the battle of Manzikert (1071). They continued pushing forward and the Byzantines had no other choice than to call for help the rulers of Western Europe. This pleas led Pope Urban II to call for a Council of Clermont, from where the Crusaders started organizing for the First Crusade.
Step-by-step explanation:
During the first Crusade, Turks Seljuks were controlling larger territories in the region. They confronted the Crusaders and even lost a couple of cities and important fortress to them. Still, they were an important factor in the region and were constantly disturbing the Crusade states that were created in the Holy land.