Answer: 5,000 years, even though the country wasn't unified
Explanation:
The Chinese formed one of the world's earliest civilization and as a result have a very rich history that goes back around 5,000 years which was way before China was first united under Qin Shi Huangdi, who reigned from 221–210 BC.
China has gone through so many historical events and after the unification under the Qin, records have been extensively kept to show the development of the world's most populous nation.
