During the period of the crusades, warfare between Christians an Muslims lasted nearly years.

200 years

Explanation:

The "Medieval Crusades" were Western Christian expeditions to liberate from the Muslim domain the S. Sepulcher of Christ in Jerusalem, which was being destroyed by the Ottoman, Muslim Turks. They began in 1095 and end in 1291, when the Turks returned to the Holy Land. The crusades were marked by frequent quarrels between Christians and Muslims. As you can see from the length of the above, the war between Christians and Muslims lasted almost 200 years.

Warfare between Christians and Muslims lasted nearly 200 years.