Question

What landform blocked contacts between the people in northern China and those in southern China?

Answer 1

Huai River Qin Mountains Line landform blocked contacts between the people in northern China and those in southern China.

Explanation:

Huai River Mountains Line is the landform that is setting out as the dividing line to be located as between the northern and southern China. It is located at the region of somehow midway between the Yellow River and Yangtze.

Answer 2

Answer is: geographical dividing line between northern and southern China is the Huai River–Qin Mountains Line.
The Huai River is located about midway between the Yellow River and Yangtze.
Qin Mountains (Southern Mountains) are a major east-west mountain range in southern China.