Answer:
It was declared an open city on 14 August 1943. Rome became the capital of the Italian Republic (established in 1946). With a population of 4.4 million (as of 2015; 2.9 million within city limits), it is the largest city in Italy.
Long Answer: Trade was very important for China because it helped China get extra surpluses exchanged for valuable supplies. China was able to get what it needed by trading what it had. Therefore trade was very helpful and played a major part in China's growth in history. It helped China grow wealthier and stronger.
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It made the population rise because more people were trying to strike it rich.