a woman is perfectly capable of riding, shooting, fighting...and can be just as clever a warrior/leader. But men can't have babies, so no matter what local customs are created, women eventually 'tend' toward occupations which allow child-bearing and raising in a way which gives the society the most flexibility.

It makes me wonder whether the Amazon women pursued the warrior life only before or after prime child-bearing age. Perhaps for a brief period, women from other grops were captured to bear children, while the 'true' member-women were out fighting? Stranger things have happened.