Why was the Chang Jiang river important to the people of China

They were very culturally and economically dependent on it.

Explanation:

The largest hydro-electric dam in the world, the three gorges dam.

The Changjiang has always been an important means of transport for goods into and out of China's interior. In the past, river travel was not easy due to the rapids. Boats often had to be rowed through the most dangerous parts.