[jimtorr]

Trade activity at the port peaked twice, in the first century and again around 500, before it ceased altogether, possibly after a plague.

Is this about the right period for a plague of Arab invaders? True Arabs this time, from Arabia.

[blam]

"Trade activity at the port peaked twice, in the first century and again around 500, before it ceased altogether, possibly after a plague.

Is this about the right period for a plague of Arab invaders? True Arabs this time, from Arabia.

"540 AD" (could this be the '500' event?)

[KellyAdmirer]

The Byzantines lost Egypt around 640 to the Arabs. Sounds to me about the right time for this port to lose its usefulness.