Fustat (الفُسطاط), also Fostat, was the first capital of Egypt under Muslim rule, and the historical centre of modern Cairo. It was built adjacent to what is now known as Old Cairo by the Rashidun Muslim general 'Amr ibn al-'As immediately after the Muslim conquest of Egypt in AD 641, and featured the Mosque of Amr, the first mosque built in Egypt. The city reached its peak in the 12th century, with a population of approximately 200,000. It was the centre of administrative power in Egypt, until it was ordered burnt in 1168 by its own vizier, Shawar, to keep its wealth out of the hands of the invading Crusaders. The remains of the city were eventually absorbed by nearby Cairo, which had been built to the north of Fustat in 969 when the Fatimids conquered the region and created a new city as a royal enclosure for the Caliph. The area fell into disrepair for hundreds of years and was used as a rubbish dump. Today, the ruins of Fustat lie within the modern district of Old Cairo, with few buildings remaining from its days as a capital. Many archaeological digs have revealed the wealth of buried material in the area. Many ancient items recovered from the site are on display in Cairo's Museum of Islamic Art. Fustat was the capital of Egypt for approximately 500 years. After the city's founding in 641, its authority was uninterrupted until 750, when the Abbasid dynasty staged a revolt against the Umayyads. This conflict was focused not in Egypt, but elsewhere in the Arab world. When the Abbasids gained power, they moved various capitals to more controllable areas. They had established the centre of their caliphate in Baghdad, moving the capital from its previous Umayyad location at Damascus. Similar moves were made throughout the new dynasty. In Egypt, they moved the capital from Fustat slightly north to the Abbasid city of al-Askar, which remained the capital until 868. When the Tulunid dynasty took control in 868, the Egyptian capital moved briefly to another nearby northern city, al-Qatta'i.