Why is 4000
b. c an important date?

The period that started 4000 b.c. is important because it is the period when the earliest civilizations flourished and inventions were made. Earliest known civilization arises in Sumer (4500–4000 B.C.). Earliest recorded date in Egyptian calendar (4241 B.C.). Hope this answers the question. Have a nice day.

Icould be wrong but i would say b.