555
> Use trading posts to trade 100,000 units of goods in a single town.
As with the trader achievement, not a hard achievement to complete, but will take a long time.
Tips
- Build a large number of trading posts to speed up your trading.
- Consider building an economy based on trading for this one - if you can import raw materials, process them (such as creating firewood from logs), and sell for a profit, you'll be able to use this profit to buy in food.