Ground trade – consists of two parts – trade in the usual goods and trade in resources. Trade in the usual goods between two next provinces depends on trading constructions, from presence of roads and from the total population in the next provinces. Construction of trading buildings gives a gain of trade in a province, but does not give its neighbours.
Final profit on trade is the sum of trading incomes of all next provinces.
Trade in resources is arranged differently. It does not depend on quantity of the population in a province – at any population the income of trade in resources identical. It is influenced with trading constructions of city.
Therefore trade in cities brings more money. It is possible to create for different fractions a chain of provinces with different resources. The trading way (Silk road) which will be very important for the world of these fractions, will turn out. Those fractions will be like trade coallition, and War will try to destroy it.