Who did the Egyptions fall to the second time?
The Arabs, now firmly in control of Syria and the Levant, sent frequent raiding parties deep into Asia Minor, and in 674–678 laid siege to Constantinople itself. The Arab fleet was finally repulsed through the use of Greek fire, and a thirty-years' truce was signed between the Empire and the Umayyad Caliphate. However, the Anatolian raids continued unabated, and accelerated the demise of classical urban culture, with the inhabitants of many cities either refortifying much smaller areas within the old city walls, or relocating entirely to nearby fortresses. Constantinople itself dropped substantially in size, from 500,000 inhabitants to just 40,000–70,000, and, like other urban centres, it was partly ruralised. The city also lost the free grain shipments in 618, after Egypt fell first to the Persians and then to the Arabs, and public wheat distribution ceased.The void left by the disappearance of the old semi-autonomous civic institutions was filled by the system called theme, which entailed dividing Asia Minor into "provinces" occupied by distinct armies that assumed civil authority and answered directly to the imperial administration. This system may have had its roots in certain ad hoc measures taken by Heraclius, but over the course of the 7th century it developed into an entirely new system of imperial governance. The massive cultural and institutional restructuring of the Empire consequent on the loss of territory in the 7th century has been said to have caused a decisive break in east Mediterranean Romanness and that the Byzantine state is subsequently best understood as another successor state rather than a real continuation of the Roman Empire.
the Arabs