The 4th millennium BC spanned the years 4000 through 3001 BC. Some of the major changes in human culture during this time included the beginning of the Bronze Age and the invention of writing, which played a major role in starting recorded history.
The city states of Sumer and the kingdom of Egypt were established and grew to prominence. Agriculture spread widely across Eurasia.
World population growth relaxes after the burst due to the Neolithic Revolution. World population is largely stable, at roughly 50 million, with a slow overall growth rate at roughly 0.03% p.a.