The Aksumites of ancient Ethiopia were one of the great civilisations of the ancient world.
At their capital of Aksum they erected the largest standing stones in Africa, one of which was taken to Rome by Mussolini
in the late 1930s (and returned in 2008). At the height of their power their empire stretched west into the Sudan and across the Red Sea into
Arabia, and they traded with the Mediterranean world and India. Only three other contemporary civilisations - the Romans,
Persians and Kushans - issued gold coins.
The first king to coin was Endubis about 290 AD. His coins bear Greek legends and pre-Christian symbols. The king's bust is in profile on both obverse and reverse, but his eyes and shoulders are facing following Egyptian conventions. Like many Aksumite kings he is otherwise unknown, so the coins are a key source for Aksumite history.
The conversion of Ezanas to Christianity, variously dated from about 330 to 360, is reflected in the replacement of the pre-Christian symbols by the cross, which also becomes the usual reverse type on the silver and copper. The cross (or crown etc) may have a gold inlay applied. This unique and unexplained phenomenon must have been very labour-intensive. Gold coins continue to have the king's bust on both sides.
One of the few other minting kings known to history is Kaleb who invaded Yemen about 520 in support of persecuted Christians.
On the later silver and copper coins the local Semitic language Ge'ez replaces Greek, and Christian legends like "through Christ he conquers" and mottoes like "joy and peace to the peoples" appear. Byzantine influence is apparent with the facing busts seen on later copper coins. Armah, one of the later kings to issue coins, used a novel design on his coppers with the king enthroned.
With the loss of Yemen to the Persians and the rise of the Arabs the Aksumites lost their foreign trade and abandoned Aksum.
The coins, though not in general as rare as they once were, are still scarce and many types are extremely rare. Anonymous copper coins are the ones most often seen. One large hoard of over 800 gold coins was found at al-Madhariba near Aden in the late 1980s.
The best book on the coinage in English is Aksumite Coinage by Munro-Hay and Juel-Jensen.
(Updated summary of a talk given to the London Numismatic Club on 7 Sep 2000 and the Oriental Numismatic Society on 14 Nov 2000)