I believe you're referring to the Makurians, the most dominant Nubian kingdom of the period? The Nubian Spearmen in the game are not representative of Makurians but of Nubians in general. I believe they're meant to represent the slaves taken from the border provinces and and possibly other non Nubian sub-Saharan African peoples. I have them modded to throw javelins to give them some more versatility.