The Humans of the Known World are pretty generic. There are many different ethnicities, just like on our world. and if you read through the Gazateers it is obvious which real-world cultures they emulate.
Essentially any Real world culture you wish to emulate, there is a race of humans that are equivalent to it in the known world. Talk to your DM for ideas, or Read the “Mystara Player’s Guide”
Baldwins Abroad 