Juba2, you keep referring to 'Numidian' and 'expansion' as if the various Numidian peoples were a unified front; in fact, the situation was entirely different. Except for very rare occasions there were a number of smaller kingdoms rather than a single kingdom. Certainly they were expansionist, but purely amongst each other. All in all, other than in opposition to local empires they had little influence on the flow of history, whereas (to cite your examples) the Saka played a major role in the east against the Indo-Greeks, and Saba was a commercial hub of major importance for trade between Egypt and India and was an expansionist power in the region in its own right.

However, I don't deny that a Numidian kingdom would be great as a new faction in EB2. But I do believe that, considering the constraints on faction slots in RTW, that the current factions had a greater impact on the history of the area depicted in EB and are more necessary to include.