Well, the chinese big secret was silk. So that would be my best guess.
The very last dinosaur died in 1927.
Answer:
2
Explanation:It improved and increased trade and travel across the empire.
Pharos is a pretty good choice
Depending on what you mean, it changed when the north saw that slavery was not just, and started goin on the attack on it. Which lead to the whole civil war of confederates vs the union
