Does this help?
it explains what your looking for
<span>Their progress and wealth is highly dependent on the harvests, and
the price of grain. They probably have to import some industrial
products and if they had a bad year (weather, other catastrophies, poor
technology) they can't get the necessary amount of industrial products
in exchange for their surplus e. g. in grain. </span>
Raw material extraction
manufacturing
distribution
and retail <span />
