At the time of the Muslim conquest in 21/642, the great majority of Egyptians were Christians, living alongside a significant community of Jews. The site of Babylon - chosen by the Muslim conquerors to build their new capital - was apparently unoccupied. However, the adjoin¬ing area was inhabited by a large, native, non-Muslim population living on the right bank of the Nile, though they were possibly not strongly urbanised. Moreover, several churches and monasteries were located in the surroundings of the so-called Qasr al-Sham˛, the Roman fortress of Babylon. The new capital, Fustat, became somewhat different from the other amṣār of the Arab world in that from very early on in its life groups from different religions - Muslims, Christians and Jews - lived side by side in the same space. The emerging need for all three groups to co-exist was the cause of specific problems which the conquerors had to manage. They achieved this by erecting spatial and legal boundaries between themselves and the conquered peoples, which served not only to organise the society of Fustat, but also to prevent any risk of assimilation.

These measures were all the more necessary as the conquering Arabs were a minority in comparison to the Christian population which was numerically superior, including in urban areas. However, the Muslim community required the services of the Christian and Jewish populations and had therefore to find a way to deal with them. The first issue was spatial: where would the non-Muslim communities live? Where would that be in relation to the Muslim population? Not too close to the Muslim people but also not too far from the administrative capital. It seems that this was not a straightforward question of spatial separation. No deliberate policies to segregate non-Muslim and Muslim groups have been identified during the medieval period. It seems more likely that the Christians had their own areas, centred on their religious buildings.