Describe the economic and political factors involved in building a network of roads canals and railroads

answer; /// i believe that the correct answer is (d)the huang he river valley;

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).

they both built pyramids.