When Aksum, also spelled as Axum, was in it's golden age it controlled several areas including Egypt, Djibouti, etc totalling to 1.25 million square kilometers . Aksum was a very cultural and economic center. King Ezana converted Aksum to christianity in the years 325 to 328, they were the first state to use the image of the cross on their coins. The main source of the empire's wealth came from control over foreign trade. In the third and fourth centuries AD rulers began importing several valuable items such as silver, gold, wine, and olive oil, and exporting items such as brass, copper, and glass crystal. They also exported items that were medicinal or used in burials, making Rome and Greece dependent on Aksum's trade. King Ezana is known as one of the best rulers Africa has ever known. A few of the many things he did were embracing christianity, establishing military campaigns, and making several structures.