Here are a couple of links that you may find interesting. I did. The first is from Real Time Economics, one of the blogs of The Wall Street Journal. It highlights some recent research that sees a correlation between trade and peacetime. From reading the post, I get the impression that the authors of the study feel that the direction may run from peace to trade.
But I suggest that since it is correlation and not causation, it's possible it may run the other way. Trade promotes peaceful relations. I've read a few things that would suggest this, either directly or by implication. It's certainly worth thinking about.
The second link is to National Public Radio's Planet Money blog. The podcast (about 15 minutes long) is about globalization and the search for spices in the Middle Ages, and features a discussion with Tom Standage, author of An Edible History of Humanity. One of the more entertaining aspects of the interview was the discussion about the early Arab monopoly on the spice trade. It appears to me that the it rested (as many monopolies do) on an information asymmetry. And it was closely guarded.
And for those of you teaching World History, here's a bonus cut from All Things Considered that you may find valuable.
I look forward to reading your reactions.