Which of the following is a similarity between the Huang River and Indus Valley civilizations?
the use of bronze ritual vessels
a social class system with farmers at the bottom
the exchange of ideas with other cultures
the use of a metal currency 

How were the civilizations of the Huang River valley and the Nile River valley similar?
Both began around 4000 BCE.
Both arose in desert regions.
Both failed to develop a writing system.
Both were ruled by dynasties.