Answer:
#1 Qin dynasty unified China for the first time in history. ...
#2 It had hugely influential figures like legalist Shang Yang and reformer Li Si. ...
#3 The writing system of China was standardized. ...
#5 The precursor to the Great Wall of China was built during the Qin era
The 3 key factors that led to the decline of the Han empire are disease, political problems, and the inability to maintain order of the public. The fall of the Han empire was mainly caused by emperors who neglected their duties.
Step-by-step explanation: