It more or less bordered or was really close to Egypt, and it was on the very coastal edge of the African continent, as close as is possible to the Arabian Peninsula, and even conquered territory outside Africa. And if the conquered parts are included, it was somewhat east as well at the very least. Did it only conquer in that direction? There are the Adwa mountains (and even the active stratovolcano Adwa), somewhat separating Axum from its south-western direction further into Africa. The capital Axum was at a very high elevation in the highlands, like more than 2000 meters above sea level, and relatively close to the other major cities. Deserts might also have separated stretches of the empire to its west. It also must have had a lot of foreign influence, as per the Greek writing on some of its coins. And the capital Axum itself was relatively close to the coast. And one description I found just mentioned coastal or near-coastal Axum cities, not cities much further inland. Adulis was coastal, and Matara like Axum was not far from the coast. I do not know if it had any other cities. One source mentions Ptolemais Theron as a coastal city.
And then some writers describe the Aksum empire as highly cosmopolitan, like Adulis having a large Greek population.
If it had partial natural borders like deserts, mountains and an active volcano, somewhat separating it from the rest of Africa in its south-western and western direction, and sizable numbers of Greeks and other peoples, and located on the very edge of Africa as close as possible to the Arabian Peninsula, it doesn't really seem to me to be the best example, upon closer examination. I can sort of understand why you would mention it as an example, though
Aksum for a start.