Some use of an oil or related product of a sort?
Snails.
Per capita production of ******** politicians?
Working donkeys, per capita.
Well it doesn't seem to have much to do with level of life or income either, since i am sure coastal Asia Minor is far better off than Cappadocia.
Perhaps you could say what color (cyan-like or light brown-like) signifies the "positive" (if the map is about such a notion that is) ?
The number of snails found on whales flying at 500 metres above sea level.
Spiders.
(They get everywhere.)
Vultures?