Kingdom of Aksum
The Christian trading empire of the Ethiopian highlands that a Persian prophet ranked beside Rome, Persia, and China, and minted sub-Saharan Africa's first coins.
Around the year 250 the Persian prophet Mani drew up a list of the world's great kingdoms, and he named four: Rome, Persia, China, and Aksum. The last was an African empire in the highlands of what is now northern Ethiopia and Eritrea, and for a moment it stood in that company on its merits. Aksum grew rich as the middleman of the Red Sea, taking a cut of the trade that flowed between the Roman Mediterranean and India, and it left behind coins, cathedrals, and stone towers to prove it.
The middleman of the Red Sea
Aksum's fortune was geography put to work. Its Red Sea port of Adulis funneled African gold, ivory, and tortoiseshell out to the wider world, and Roman glass, wine, and cloth in. Merchants from Egypt, Arabia, and India passed through, and the kingdom taxed the traffic in both directions. The clearest sign of how seriously Aksum took commerce is that it minted its own money. From the late third century its kings struck coins in gold, silver, and bronze, the first state in sub-Saharan Africa to do so, stamped with Greek or Ge'ez legends and meant to be trusted by foreign traders who had never seen the place.
That wealth was written into stone. On the edge of the capital the Aksumites raised carved granite stelae to mark the tombs of their kings, the tallest monoliths ever quarried and stood upright in the ancient world. The greatest of them, about 33 meters tall, seems to have shattered as it was being erected. A 24-meter neighbor still stood until 1937, when Italian troops carted it off to Rome on Mussolini's orders; Italy finally returned it in 2005. The tallest one still standing, King Ezana's stele, reaches 21 meters.
The king who put the cross on his coins
That same King Ezana made Aksum's most lasting decision. Around 330, under the influence of Frumentius, a shipwrecked Christian from the Roman world who became his tutor, Ezana converted, and Christianity became the religion of the state. Aksum was one of the first kingdoms anywhere to adopt it officially, and Ezana advertised the change in the most public medium he had: he replaced the pagan crescent and disc on his coins with the cross, making Aksum the first state in history to mint Christian coinage. That church never went away. It is the direct ancestor of the Ethiopian Orthodox Tewahedo Church, which counts tens of millions of believers today. Aksum's cathedral, Our Lady Mary of Zion, is where Ethiopian tradition insists the Ark of the Covenant still rests, brought from Jerusalem by Menelik, the son of Solomon and the Queen of Sheba.
What the sea gave, the sea took
Aksum's rise and fall both ran through the Red Sea. When Arab armies carried Islam out of the peninsula in the seventh century, the sea lanes that had made the kingdom rich swung toward the new Muslim ports, and the trade that fed Aksum drained away. The mints fell silent, the capital shrank, and the center of Ethiopian power drifted south into the mountains. But the faith outlived the empire. The stelae still stand on the Ethiopian plateau, and in a guarded chapel below them a monk still keeps watch over what his church swears is the Ark, in the town a Persian prophet once ranked beside Rome.