when did china and india interact?

Answer 1

Change your question to
When did China and India intercourse?

Answer 2

Contacts with the Kushan Empire led to the introduction of Buddhism to China from India in the first century.

--Before this period China was in its "Warring States" and had any Feudal clans. They most likely were not organized enough to send envoys to India. The Silk Road also probably expanded China's knowledge of it's surrounding neighbors. The silkroad also flourished during the 1st century.