Ah, but when you're fighting with swords and bows, war stops being a numbers game and becomes a contest of skill, and we all know Europe's age old tradition with sword and shield. In fact, the most likely scenario in a world without gunpowder is a world predominantly ruled by the European nations, Japan remaining a small, isolated country but gaining power as a land that lives and dies by the sword, and possibly a smaller version of Russian simply based on the tenacity of their fighters.