The Kingdom of Aksum is notable for a number of achievements: its own alphabet, the Ge'ez alphabet, which was modified to include vowels, becoming an abugida (writing system in which consonants are inherently associated with vowels). In the early times of the kingdom, giant Obelisks to mark King's (and nobles') tombstones were constructed, the most famous of which is the Obelisk of Aksum.

Under King Ezana’s rule, Aksum adopted Christianity and replaced its former polytheistic and Judaic religions around the year 325. This gave rise to the present day Ethiopian Orthodox Tewahedo Church and Eritrean Orthodox Tewahdo Church. Since the split with Rome after the Council of Chalcedon, it has been an important Miaphysite church, and its scriptures and liturgy are still in the Ge'ez language.

A story recorded by Rufinus has it that at that time, a foreign boy named Frumentius was made a slave of the royal court, and was later made a tutor to the royal children. When the king died, the queen asked Frumentius to help rule Aksum. Frumentius declined his promised freedom and remained until the queen's son, Ezana, was old enough to rule. Frumentius also established a number of Christian churches, and then when Ezana became king Ezana made Christianity the official religion of Aksum. The custom of a slave teaching kings remained an important tradition for the next few hundred years.

Aksum was a cosmopolitan and culturally important state. It was a meeting place for a variety of cultures including Egyptian, Arabic, Sudanic and Indian. The major Aksumite cities had Sabean, Jewish, Nubian, Christian, and even Buddhist minorities.

The Kingdom of Aksum was also the first African polity to issue its own currency. From the reign of Endubis up to Armah, gold, silver and bronze coins were minted. Issuing coinage in ancient times was seen as an act of great importance because it showed the world that the Aksumite kingdom considered itself to be equal to its neighbors. The presence of coins also simplified trade, and was a useful instrument of propaganda and a source of profit to the kingdom.

Aksum began to decline in the 7th century, and the population was forced to go farther inland, and was eventually being defeated around 950. Local history tells of a Jewish Queen named Yodit or "Gudit“defeated the kingdom and burned its churches and literature. While there is evidence of churches being burned and an invasion around this time, her existence has been questioned by some modern authors. Another possibility is that the Aksumite power was defeated by a queen named Bani al-Hamwiyah, possibly of the tribe al-Damutah or Damoti. After this period, the Aksumite kingdom was succeeded by the Zagwe dynasty in the eleventh century or the twelfth century, although it was limited in size and scope. However, Yekuno Amlak, who killed the last Zagwe king and founded the modern Solomonic dynasty, traced his ancestry and his right to rule from the last king of Aksum, Dil Na'od.