That would be a cool wat to do it but somewhat hard. You'd need to get the script to check for what locations have your resource(in this example, I'll use Iberia) and have it recheck to figure out if you still own it. Then there are the logic issues of people importing the resources or rich people buying resources personally or having armour commisioned. I mean, you do get alot of fancy armours from the steppes. The only reason you don't see uber armour on desert units is the heat. Even then there are the exant specimens of Egyptian scale armour.