Here's what I can do as a region lord:
Buy food from any region in range and sell to Raviel
Sell food from any region in range and sell to Raviel
So I can travel to Storms Keep and purchase food for Raviel, or sell food to Storms Keep from Raviel.
Here's what my trader can do, with his 562 mile range:
From Paisly, I can purchase food as far south as Candiels Fields, and as far north as Vasgew. So I could buy food from Candiels Fields and sell them to Saffalore, or anyplace in between. Or west to Twainwood, or east to Nebel. So I an buy food from Terran, Barca, and Aurvrandil, and supply all 3 major cities of D'Hara, assuming those region lords of buy orders in place.
Or, I could travel to Vasgew, and broker a deal between Lowervia and Paisly. Or do the same to cover most of Madina's regions from Candiels Fields.
Here's what we can do with multiple traders and a cooperative region lord:
Trader A can travel to Vasgew, buy food from Lowervia, and sell to Paisly.
Trader B can travel to Candiels fields, buy food from Paisly, and sell to Bol.
For reference, that's two (good) traders, each with a range of about 560 miles, selling food over a distance of about 2000 miles. Only 2 buy and 2 sell orders are needed.
And of course, since it's unlikely that Paisly will be selling food, you can think of all that as the effective 'buying range' of two traders in range of Paisly--over half of western Dwilight.
And, we can do the same thing from the Desert of Silhouettes, but I'm not sure of the specific regions in range.
Trading over the sea routes would be an excellent addition. With those, we'll be able to travel to Golden Farrow or Mimer and trade within 500 miles of those regions, and send the food back to D'Hara.
