A caravan was a group of people who .
A.
lived in the desert as a nomadic tribe
B.
frequently traded goods with one another
C.
were sent by trading posts to assist travelers
D.
traveled together across the desert for safety reasons
Where did people have to work with great organization to be successful at farming? a. on the yellow river basin c. on the hangzhou bay b. on the yangzi river basin d. on the hubei basin