The 4th millennium BC.
The third millennium BC.
The 4th millennium BC began 4000 BC and ended in 3000 BC. The 4th millennium BC marks the beginning of the bronze age and of writing.
Every millennium, including the 5th millennium BC, is 1000 years.
4th millennium BC through 2000 BC
From the year 1001 to 2000.
It was a very long time ago in the bc land.
2000 BC through 1001 BC
Romanians, 3rd millennium BC
swimming started in the 3rd millennium BC.
eighth and sixth
Nobody knows for sure but it is estimated at about 2500 BC.