How many years is 4000 BC?

B.C. refers to a few years before B.C., and after A.D. refers to a few years after A.D. The specific algorithm is: for example, 200 B.C. is the 3rd century B.C., because before all centuries, 1 should be added, and 200 is originally the 2nd century, and 1 is the 3rd century B.C.. If it is 200 years after AD, it is the 3rd century after AD. What is more special is 0 year, which is 1 century, because 0+ 1 ...

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Therefore, 4000 BC is between 3000 BC and 3099 BC.