Final answer:
Aksum's trade significantly expanded under King Ezana in the fourth century CE, making the kingdom prosperous through trading activities and military conquests while also marking its conversion to Christianity.
Step-by-step explanation:
During the reign of King Ezana, Aksum's trade with the African interior experienced significant expansion, making the kingdom wealthier and more powerful. This occurred in the fourth century CE, a period when King Ezana spearheaded successful military campaigns and subjugated nearby regions like the Kingdom of Kush. Under his rule, Aksum became an important hub for trading commodities such as gold, ivory, and spices. Moreover, the societal and religious landscape also transformed as Ezana converted to Christianity and instituted it within the Aksumite kingdom, symbolized by the Christian cross on Aksumite coins. This conversion to Christianity marked a significant shift for the Aksumite state and marked its influence spanning from the African interior to across the Red Sea.