Question

Why did the relationship between Chinese and nomads grow tense?

Answer 1

The nomads caused invasions that weakened the Zhou dynasty, leading to a violent and tense relationship between the Chinese and nomads.

Invasions lead by the nomads and intrusion within a country would obviously lead to tense relationships if any at all, causing the Zhou dynasty to attempt to block and fight the nomads back, thus the violent relationship.

Hope this helps!