A trend of increased-scale economies can be observed through history as city-states have given way to the increased military power of centralized Medieval kingdoms. Many of those expanded into Early Modern kingdoms as advances in military technology make it possible for kings to extend the territory under their control. Even empires have gotten bigger. Modern-day Germany was once considered an empire, as were Switzerland and the Netherlands. Today these polities are states in a modern form of empire, the EU. Similarly, the emergent United Colonies of America was considered to be an empire within the British Empire, with the individual colonies being viewed on both sides of the Atlantic as Early Modern kingdom-level polities on par with the states of the E.U. in the twentieth century. Similarly in China, as kingdoms were added, an old form of empire took shape. Because these enlargements came about gradually over centuries, it has been difficult for the human mind to recalibrate how the modern large empire-scale economies should be designed to take into effect the distinct challenges of the scale. We can see such an adjustment in the case of China as economic centralization came to be replaced by regulated markets, albeit with a sizeable involvement still of the government in the economy.
The Emperor Kangxi of the Qing Dynasty. He ruled for 60 years, greatly expanding the size of the empire. (Source: Chinahighlights.com)
The full essay is at "The Case of China."