Why did the Industrial Revolution happen in Europe, rather than China? Joel Mokyr thinks fragmentation was the key:
In Europe, no one ever succeeds in unifying it, and you have continuous competition. The French are worried about the English, the English are worried about the Spanish, the Spanish are worried about the Turks. That keeps everybody on their toes, which is something economists immediately recognize as the competitive model. To have progress, you want a system that is competitive, not one that is dominated by a single power. […] I think that is the major difference. It isn’t just that China doesn’t have an Industrial Revolution, it doesn’t have a Galileo or a Newton or a Descartes, people who announced that everything people did before them was wrong. That’s hard to do in any society, but it was easier to do in Europe than China. The reason precisely is because Europe was fragmented, and so when somebody says something very novel and radical, if the government decides they are a heretic and threatens to prosecute them, they pack their suitcase and go across the border.
Unity is a decelerator.