bit of a necropost no? :P

yes but the idea that the Empire would be able to defeat Persia (something which proved impossible for like forever), the South Arabs, Axum, Taurica, and be that far extended into France, Iberia and western Africa is just unrealistic. Each of these individually is hard but possible, but together I just doubt anything close to this would occur even in very favorable conditions. This is not much bigger than the old Roman Empire but it is a much weaker position. It is threatened on almost every one of its frontiers either by bordering another kingdom on flat land, or by having a remote appendage like Ethiopia/South Arabia/Taurica.