Yes, in Civilization. I just found an article, published in an Italian games review in January 87 (!) by Mr. Giancarlo Mercuri.
This is the translation:

We missed them. CIVILIZATION without slaves is like Waterloo without Napoleon.
I missed this important exchange factor since the first games I played. Immediatly came the dilemma about how to insert them within the commodity cards: how many cities do you need to buy slaves? At start I was leaning to put them around the middle stacks, but a final consideration brought me to insert them in the ninth stack: in the ancient times, and even later, the most precious slave was the strongest (both phisically and mentally), the smartest, the most raffinate. A "good" with a market value strongly influenced by the qualities of the slave himself. While for some goods are valid the pricing criteria "best quality means higher price" for slaves quality was an indispensable condition for selling. This was probably also for young and still to train slaves. These considerations bring evaluating slaves at stack nine. Slave's value is the same of gold.

(here Mr. Mercuri continues in his analysis about slaves condition at that times and I will omit for brevity - Upon request I can send a fax of the original article)

Continues:
In the game I inserted four slave cards to mean the large diffusion of slavery. The wealth you can reach with slaves is counterbalanced by the danger of the slaves themselves as you can see in the following slaves special rules:

Slaves are to be considered a stack 9 card. Can be traded, bought with 18 treasury tokens, etc.
If a player is hit by Civil Disorder and has two or more slave trade cards in his hand he will resolve the calamity following these rules (numeration follows the Civilization Rule).

22.2.9.1 If the victim has more than three cities he must reduce all cities over the third.
22.2.9.2 If the victim has LAW (but not DEMOCRACY) he will reduce all cities over the fourth.
22.2.9.3 If the victim has DEMOCRACY he will reduce all cities over the fifth.
22.2.9.4 The cities to be reduced are chosen by the victim.
22.2.9.5 All slave cards the victim has in his hand are discarded.

Optional:
22.2.9.6 If the victim has all four slave cards he must reduce all cities over the second (also if he has LAW or DEMOCRACY).

Thought this article had to be shared.

Raffaele

I think you are right about retelling history the right way, but I think the subject is kinda difficult.

I think not everyone want to play games on trading slaves. The gaming part though is interesting.