It would make sense, especially as reward for researching Tribalism.I'm of the opinion that the national limit on Tribes should be removed.
What is the rationale for having the national limit?
Alternatively that tribes should be awarded through events or from researching certain techs during the prehistoric.
Maybe two tribes for every civ, that researched Tribalism.
Also raising limits for hunter type units to lets say 10 or 15 could help AI too.
citizen problems. Cause that is all that Option really does.