How did the Han Dynasty influence surrounding countries?

Well, hereunder is the info I know:
1. Due to the great economic strength, Han was the one of two leading empires in that time (the other is Roman). The territory was very large then to attract the attention of the world.
2. Zhang Qian was appointed to visit the west region. He firstly opened the Silk Road, which later played an important role in international trading.
3. Diplomacy and cultural exchanges with North Korean and Japan were prosperous then.