During the 10th century, Acre was still part of Jund al-Urdunn. Local Arab geographer al-Muqaddasi visited Acre during the early Fatimid Caliphate in 985, describing it as a fortified coastal city with a large mosque possessing a substantial olive grove. Fortifications had been previously built by the autonomous Emir Ibn Tulun of Egypt, who annexed the city in the 870s, and provided relative safety for merchant ships arriving at the city's port. When Persian traveller Nasir Khusraw visited Acre in 1047, he noted that the large Jama Masjid was built of marble, located in the centre of the city and just south of it lay the "tomb of the Prophet Salih." Khusraw provided a description of the city's size, which roughly translated as having a length of and a width of . This figure indicates that Acre at that time was larger than its current Old City area, most of which was built between the 18th and 19th centuries.