The coastline of the state of California

The street your school is on

The border between the U.S. and Canada

The border between Massachusetts and Rhode Island

China has never been successfully invaded

The wall still serves an important strategic purpose

There are still many nomadic tribes north of the Great Wall

It's still an important symbol of Chinese culture

A dependence on agriculture

A lack of permanent towns and villages

A warlike nature

An advanced social structure

To prevent enemy armies from seeing what was on the other side

To prevent horses from getting over it

To prevent attacks with arrows and spears

To prevent individual people from climbing it

A succession of rulers from a single family

A system of government similar to democracy

A warlike nomadic tribe

Another word for "empire"