1. What happens if you extend the dates back further?
2. It's interesting to see China's dominance decrease and rise again over a long time period. I knew this but it's interesting to see quantitatively. It leads me to wonder if a simple rise-fall pattern is necessarily "natural" or if more variation exists.
3. It seems like in certain cases, the fall of prominence isn't the same. I don't think of the Netherlands as ever falling into irrelevance or destitution, just maybe declining in power as the major economic and military power. This seems different from more dramatic boom-bust cycles. Maybe I'm wrong about this, as I know relatively little about Dutch history.
4. It's tempting to predict major from transitions but they don't seem to correlate as well with the rise and fall curves, possibly because in actuality there's so many and lots of the major conflicts involve coordinated interests of smaller powers, rather than single interests of single powers.
5. I wonder if some of this is oversimplified because of changes in what constitutes a nation-state. That is, what we recognize as "China" wasn't always as such, and many European states may become better understood as part of the EU in the future.