Some of this iron was put to use in new plows, which enabled agriculture to boom, thereby supporting population growth. Porcelain was of such high quality that it was shipped throughout the world, which is why we now call it China. And there was so much trade going on that the Chinese ran out of metal for coins, leading to another innovation, paper money. And by the 11th century, the Chinese were writing down their recipe for a mixture of salt, peter, sulfur, and charcoal that we now know as gunpowder. That becomes kind of a big deal in history, paving the way, as it does for modern warfare and arena rock pyrotechnics and... Oh, that's why! Not so dark after all. Thanks for watching.