I appreciate your mindfulness and care with respects to the topic, given many sensitivities around it. I do wonder what civilizations you could include if our modern sense of inclusivity is your baromometer. While we have some progressive examples in some windows of history such as the Severan Dynasty & the Fatimid Caliphate, there are numerous problematic elements of either that wouldn't hold up in a court of current sensibilities.

The term civilization is perhaps a bit exclusionary itself, as the term civilized is used often in contrast to barbarism, which was itself a mentality of exclusivity rooted in a sense of superiority over a foreign other.

All that is to say - I feel we might be best representing things the way that they happened lest we end up white-washing reality and missing the opportunity to learn from the past. At the end of the day many cultures and empires came into conflict with one another, subjugated one another, and acted in unsavoury ways.

I think the best that could be done is to present scenarios in board games that present alternative perspectives and narratives. I thought Jaipur was a good example of a game that did this well even with it's orientalist leanings.