The reference to Huns in a military context circa 400AD might be from Letter 78 of Synesius found online here which I also post below in full - Synesius is talking about a troop of Hunnic cavalry - more of which can be read here

And a further mention but Synesius here and here. Although these were stationed in Cyrenaica and not in Aegypt but close enough!


Nothing could be more advantageous to Pentapolis than to give honor to the Unnigardae, who are excellent both as men and as soldiers, in preference to all the other troops, not only those who are termed native troops, but also all that have ever come into these districts as auxiliary forces.

The truth is that these latter, even when they are much superior to the enemy in numbers, never yet gave battle with courage, but the Unnigardae in two or three engagements, with a handful of forty men, engaged an enemy of over a thousand. Assisted by God and led by you, they have gained the greatest and most glorious victories.[ 1] The barbarians had scarcely shown themselves when some were killed on the spot and others put to flight. They still patrol the heights, ever on the watch to drive back attacks of the enemy, like whelps springing out from the courtyard, that no wild beast may attack the flock.

But we blush when we see these brave fellows weeping in the very midst of their strenuous service in our cause. It is not without sadness that I have read a letter which they have sent me, and I think that you also ought not to be remain unmoved at their prayer. They make a request of you through me, and of the Emperor through you, which it were only fair that we ourselves should have made, even had they been silent, to wit, that their men should not be enrolled amongst the native units. They would be useless both to themselves and to us if they were deprived of the Emperor's largesses, and if, moreover, they were deprived of their relays of horses and of their equipment, and of the pay which is due to troops on active service. I beg of you, who were the bravest among these, not to allow your comrades-in-arms to enter an inferior rank, but to let them remain without loss of their honors, in the security of their former position. This might well be, if our most kind Emperor should learn through your representation how useful they have been to Pentapolis.

Make of the Emperor another request on my behalf in your letter, namely, to add one hundred and sixty of these soldiers to the forty that we have already; for who would not admit that two hundred Unnigardae, with the aid of God, like unto these in heart and hand, and no less docile than brave, would suffice, when commanded by you, to bring the Ausurian war to an end for the Emperor? Or what use are many levies and the annual cost of maintaining the troops here? For war we need hands, not a list of names.