Why would we classify china as an empire during this time?

1) China had an emperor/empress, which is commonly used to refer to a ruler of an empire.

2) The land in which the chinese empire govern rivals that of Rome, Persia, and other well-known 'empires' of Europe.

3) China had established and secure borders, well-developed literature and writings, a national currency that was used throughout it's land, a large standing army, taxes on both currency, trade, products, and wealth.

4) China had established trade with other civilizations.

etc.

4 copper and gold, the california gold rush is why im pretty sure.