According to the online article about the great wall of china, one reason the wall was built was to protect merchants who were traveling along the a. zhou road b. silk road c. vietnam road d. xia road

This term refers to the number of people per unit area (usually a kilometer or a mile). this could refer to the number of people per square mile in a city, a county, a province, a state, or a nation.

Among the many crucial themes related to politics, a central idea of politics includes the existence of

Which environmental change allowed people to travel by land between asia and north america a.human apaption to arctic environments b.the introduction to horses to north america c.the formation of ice sheets on land d.a rise in ocean temperatures