The writer, historian, and all-around badass nerd John Green gives an awesome overview of trade in the Indian Ocean.1 I really like Green’s Crash Course series on history. It’s an excellent overview of world history done in an accessible, yet high-content fashion, and it does a great job of demonstrating the complexity of history.

One thing I like about this video in particular is that it does an excellent job of demonstrating what I like to call Peaceful Trader Principle2. Roughly put, the Peaceful Trader Principle is that people who interact primarily through trade are less likely to engage in violence against one another. After all, if both parties are profiting from trade, war suddenly becomes much more expensive and, thus, less attractive. It also tends to forge other social bonds, such as commonality of religion, as in John Green’s example of Indonesian merchants converting to Islam.

This is a pretty well-established phenomenon, and it’s well-supported both in historical anecdotes like Green’s, but also in scholarly work in trade economics. Even the most cautious studies that I’ve seen say that trade only moderately promotes peace or may not promote it in every particular case.3

So generally speaking, people who trade aren’t likely to start butchering one another. Green’s video is an excellent example of that fact, and I find it a little funny that (starting at around 4:48) John Green seems surprised that the trade was so peaceful. Really, peace is the expected outcome from such a large and healthy trading community.

Peaceful self-regulation works pretty well when both parties stand to gain from the arrangement.

1 Another good overview of the trade in the Monsoon Marketplace can be found in Matt Ridley’s book The Rational Optimist.

2 If there’s a pre-existing term for this well-known phenomenon, then I’m ignorant of it. If anyone knows a pre-existing or more proper term, please let me know in the comments.

3 A quick plug here for the blog that taught me most of the (very little) I understand about Trade Economics: Trade Diversion, written by my good friend Jonathan Dingel.