The 4th millennium BC spanned the years 4000 BC to 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 (Predynastic) Kingdom of Egypt were established and grew to prominence. Agriculture spread widely across Eurasia.
An urban area is a human settlement with a high population density and an infrastructure of built environment. Urban areas originate through urbanization, and researchers categorize them as cities, towns, conurbations or suburbs. In urbanism, the term "urban area" contrasts to rural areas such as villages and hamlets; in urban sociology or urban anthropology, it often contrasts with natural environment.
The development of earlier predecessors of modern urban areas during the urban revolution of the 4th millennium BCEled to the formation of human civilization and ultimately to modern urban planning, which along with other human activities such as exploitation of natural resources has led to a human impact on the environment.