Answer:
Native Americans had never been exposed to those diseases.
Explanation:
Emperor Wu-ti launched attacks against groups that pose threats against the empire. He deemed this the right decision to solve the problem right away. He was determined to win and sent troops after troops into the battlefield. Because of this, he was able to expand China's control. On another hand, he also exhausted their resources due to allocating most of the empire's income to the military forces. He needed to look for another way to expand their income. He did this by passing a decree that the state can monopolize the salt, wine, and iron.
They had a lot of money wasted and they lost a lot of lives during this.
I am assuming you are talking about the US. So in the North they have Rocky Poor Soil.
