I've noticed some similarities between pre colonial Igbo society and ancient Greece.

The main resemblance is that of the city state.

As we know ancient Greece was not a unified body, but rather a group of small but influential governments each varying to some degree in culture & tradition.
But united under the Hellenic pantheon (ancient Greek religion).

There are parallels with Igbo variations in cultural & traditional practices but all united under one belief system, Odinani.

Classical Athens was the cultural & religuous centre of Greece.
Much like how Igbo-Ukwu was for the Igbos.

Ephesus was the most important trading port in the Aegean sea .
Onitsha was largest metropolitan trading port on the Niger river.

Sparta was the militaristic society built on warfare & conquest of her neighbours.
like Sparta, Ohofia had a strong warrior tradition renowned throughout Igboland.

Ritual slavery with was common in both ancient Greece & Igboland.

Disclaimer!
I'm by no means suggesting that Igbos & ancient Greeks are related, I just thought it was an interesting comparison to make.

Igbo kwenu!