If China had escaped Jurchen and Mongol devastation, its renaissance culture might have blossomed into a scientific revolution instead of withering into complacency and footbinding. Internal demand from a hundred million Chinese subjects, trade between an agricultural south and an industrial north, and colonization in Southeast Asia might then have been enough to tip the balance. On the other hand, possibly not; until it had the kinds of guns and armies that could close the steppes, China remained open to devastating migrations.