There are two striking facts about China. First, the country is quite large. Second, the country was remarkably large early in its history, compared to most other political units. For instance, here is China in 200 AD:
How did this happen?
Or consider a modern version of the puzzle: currently there are over one billion Chinese in one political unit, and a bit of scattering. And there are over one billion Europeans, spread in fairly significant numbers across about fifty political units. How did such a fundamental difference come to pass?
I can think of many instructive explanations for China’s early size and unity that are nonetheless derivative. For instance perhaps a common language for writing played a key role, or perhaps the civil service and the exam system bound the country together. I don’t mean to gainsay those claims, but they are not fundamental. In part they are simply alternative descriptions of China’s relatively early unity. And there still ought to be reasons why those factors were the case, and some of them seem to postdate unity. On top of that, ideally we would like the explanation to account for China’s periodic descents into fragmentation and sometimes warring chaos.
I can think of a few factors that might count as fundamental, and often they involve economies of scale:
1. There may be greater economies of scale in Chinese agriculture. One specific hypothesis is that China’s “hydraulic” system of rice irrigation favored a centralized despotic authority (Karl Wittfogel, though I’ve never found this particular view convincing, see also earlier takes on “Oriental Despotism”).
2. There may be economies of scale for fighting land battles with horses. Alternatively, when it comes to naval warfare — more common for Europe — small countries have a chance to punch above their weight, witness England and Portugal.
3. China had lower climate volatility than did Europe, and that made it easier for a more stable equilibrium to emerge. (Or the kinds of climate volatility China had mattered less for its agriculture.) Big changes in climate, in contrast, periodically overturn political equilibria, most of all when agriculture was a huge chunk of gdp.
4. China has two main, navigable rivers running east to west, the Yellow and Yangtze rivers. It also has a large space of relatively flat plains.
5. China was formed when the prevailing technologies favored size and scale, and thus size and scale were imprinted onto early Chinese political DNA. This is a bit like the “inflation” theory of the universe. (NB: This part of the explanation is arguably “accidental” rather than “fundamental.”)
6. China and Rome are with regard to size and early unity not so different, but China did a better job absorbing the “barbarians” and thus persisted as a larger political unit.
What else? With some mix of those (and other) factors in place, the more traditional detailed explanations then kick in to promote China’s size as China.
Ideally, an explanation for China’s early size and unity, and why that size and unity bounced back from so many periodic bouts of warring states, should address the following:
a. Why the mountainous Tibet also ended up as a more or less coherent nation-state, and why that too happened fairly early. That seems to militate against purely rice-based explanations.
b. Why Yunnan was absorbed into China at a relatively late date — the 17th century — but once attached did become a stable part of the country in a manner that other parts of southeast Asia did not mimic.
c. Why Korea remained separate.
d. Why the Khmer empire proved unstable and perished, despite a high level of sophistication and state capacity.
e. Why the Aztec Triple Alliance grew to a much larger size than any political unit in North America at the same time.
I am grateful to a presentation by Debin Ma, and to comments from the Washington Area Economic History Seminar (recommended!), from a seminar last night. None of them are implicated in what I have written. I look forward to Debin’s paper on this topic (here is his earlier 2012 work), and Kenneth Pomeranz is writing an entire book on the question.
Addendum: Here is the Ko, Koyama, and Sng piece (pdf).