Unimportant during the first centuries of Christianity, Jaffa did not have a bishop until the fifth century CE. In 636 Jaffa was conquered by Arabs. Under Islamic rule, it served as a port of Ramla, then the provincial capital.
Jaffa was captured during the Crusades, and became the County of Jaffa and Ascalon, one of the vassals of the Kingdom of Jerusalem. One of its counts, John of Ibelin, wrote the principal book of the Assizes of the Kingdom of Jerusalem. During the period of the Crusades, the Jewish traveller Benjamin of Tudela (1170) sojourned at Jaffa, and found there just one Jew, a dyer by trade. Saladin took it in 1187. The city surrendered to King Richard the Lionheart on September 10, 1191, three days after the Battle of Arsuf. Despite efforts by Saladin to reoccupy the city in July 1192 (see Battle of Jaffa) the city remained in the hands of the Crusaders, and on 2nd September 1192 the Treaty of Jaffa was formally sworn, guaranteeing a three year truce between the two armies. In 1268 Jaffa was conquered by Egyptian mamluks, led by Baibars. In 14th century they completely destroyed the city for fear of new crusades. According to the traveler Cotwyk, Jaffa was a heap of ruins at the end of the 16th century.