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.
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. 
Culture Near East
4100-3100 BC: the
Uruk period, with emerging Sumerian hegemony and development of "proto- cuneiform" writing; base-60 mathematics, astronomy and astrology, civil law, complex hydrology, the sailboat, potter's wheel and wheel; the Chalcolithic proceeds into the Early Bronze Age.
3500– 2340 BC; Sumer: wheeled carts, potter's wheel, White Temple ziggurat, bronze tools and weapons.  First to Fourth dynasty of
Kish in Mesopotamia. Sumerian temple of Janna at
Eridu erected. Temple at
Al-Ubaid and tomb of Mes-Kalam-Dug built near Ur, Chaldea.
3000 BC – Tin is in use in Mesopotamia soon after this time. 
3500- 2340 BC – First cities developed in Southern Mesopotamia. Inhabitants migrated from north. The
cuneiform script proper emerges from pictographic proto-writing in the later 4th millennium. Mesopotamia's "proto-literate" period spans the 35th to 32nd centuries. The first documents unequivocally written in the Sumerian language date to the 31st century, found at Jemdet Nasr.
Dams, canals, stone sculptures using inclined plane and lever in Sumer. Urkesh (northern Syria) founded during the fourth millennium BC possibly by the Hurrians. Persian plateau
Anatolia and Caucasus
Naqada culture on the Nile, 4000-3000 BC. First hieroglyphs appear thus far around 3500 BC as found on labels in a ruler's tomb at Abydos.
Predynastic pharaohs Tiu, Thesh, Hsekiu, Wazner, Ro, Serket, Narmer.
3500- 3400 BC – Jar with boat designs, from Hierakonpolis (today in the Brooklyn Museum) is created. Predynastic Egypt. c.
3150 BC – Predynastic period ended in Ancient Egypt. Early Dynastic ( Archaic) period started (according to French Egyptologist Nicolas Grimal). The period includes 1st and 2nd Dynasties. c. 3100 BC –
Sails used in the Nile.
Mastabas, the predecessors of the Egyptian pyramids.
Harps and flutes played in Egypt.
Lyres and double clarinets ( arghul, mijwiz) played in Egypt. Earliest known numerals in Egypt. Europe
Crete: Rise of Minoan civilization.
c. 4000-2000 BC – People and animals, a detail of rock-shelter painting in
Cogul, Lleida, Spain, are painted. It is now at Museo Arqueológico, Barcelona.
Arzachena & Ozieri cultures.
3600 BC – Construction of the ?gantija megalithic temple complex on the Island of Gozo: the world's oldest extant unburied free-standing structures, and the world's oldest religious structures. (See Göbekli Tepe for older, buried religious structures.)
3600- 3200 BC – Construction of the first temple within the Mnajdra solar temple complex, containing "furniture" such as stone benches and tables, that set it apart from other European megalith constructions.
3600- 3000 BC – Construction of the Ta' ?a?rat and Kordin III temples
3250- 3000 BC – Construction of three megalithic temples at Tarxien 3200- 2500 BC – Construction of the ?a?ar Qim megalithic temple complex, featuring both solar and lunar alignments. Northern Europe
Funnelbeaker culture, Scandinavia, 4000-2700 BC, originated in southern parts of Europe and slowly advanced up through today's Uppland.
c. 3300 BC – Ötzi the Iceman dies near the present-day border between Austria and Italy, only to be discovered in 1991 buried in a glacier of the Ötztal Alps. His cause of death is believed to be homicide. Central Asia East Asia Neolithic Chinese settlements. They produced silk and pottery (chiefly the
Yangshao and the Longshan cultures), wore hemp clothing, and domesticated pigs and dogs. Vietnamese Bronze Age culture. The ng u Culture, 4000- 2500 BC, produced many wealthy bronze objects. South Asia Americas Australia Sub-Saharan Africa
Sub-Saharan Africa remains in the
except for the earliest neolithization of the Sahel following the desiccation of the Sahara in c. 3500 BC.  As the grasslands of the Sahara began drying after 3900 BC, herders spread into the Nile Valley and into eastern Africa (  Eburan 5, Elmenteitan).
The desiccation of the Sahara and the associated neolithisation of West Africa is also cited as a possible cause for the dispersal of the Niger-Congo linguistic phylum.  
Based on studies by
glaciologist Lonnie Thompson, professor at Ohio State University and researcher with the Byrd Polar Research Center, a number of indicators shows there was a global change in climate 5,200 years ago, probably due to a drop in solar energy output as hypothesized by Ohio State University. 
Calendars and chronology
4000 BC – Epoch of the Masonic calendar's Anno Lucis era.
3929 BC – Creation according to John Lightfoot based on the Old Testament of the Bible, and often associated with the Ussher chronology.
3761 BC – Since the Middle Ages (12th century), the Hebrew calendar has been based on rabbinic calculations of the year of creation from the Hebrew Masoretic text of the bible. This calendar is used within Jewish communities for religious and other purposes. The calendar's epoch, corresponding to the calculated date of the world's creation, is equivalent to sunset on the Julian proleptic calendar date 6 October 3761 BC. 
3114 BC – One version of the Mayan calendar, known as the Mesoamerican Long Count, uses the epoch of 11 or 13 August 3114 BC. The Maya Long Count calendar was first used approximately 236 BC (see Mesoamerican_Long_Count_calendar#Earliest_Long_Counts.
3102 BC – According to calculations of Aryabhata (6th century), the Hindu Kali Yuga began at midnight on 18 February 3102 BC. 3102 BC – Aryabhata dates the events of the Mahabharata to around 3102 BC. Other estimates range from the late 4th to the mid-2nd millennium BC.
^ Jean-Noël Biraben, "Essai sur l'évolution du nombre des hommes",
Population 34-1 (1979), 13-25, estimates 40 million at 5000 BC and 100 million at 1600 BC, for an average growth rate of 0.027% p.a. over the Chalcolithic to Middle Bronze Age.
^ Federico Lara Peinado, Universidad Complutense de Madrid: "La Civilización Sumeria".
Historia 16, 1999.
^ Roberts, J:
History of the World. Penguin, 1994.
Gasser, Aleksander (March 2003). "World's Oldest Wheel Found in Slovenia". Government Communication Office of the Republic of Slovenia.
Australia's top 7 Aboriginal rock art sites by Australian Geographic
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Manning, Katie; Timpson, Adrian (2014). "The demographic response to Holocene climate change in the Sahara" (PDF). Quaternary Science Reviews. 101: 28-35. doi: 10.1016/j.quascirev.2014.07.003.
^ a b Igor Kopytoff,
The African Frontier: The Reproduction of Traditional African Societies (1989), 9–10 (cited afer Igbo Language Roots and (Pre)-History, A Mighty Tree, 2011).
"Major Climate Change Occurred 5,200 Years Ago: Evidence Suggests That History Could Repeat Itself". Archived from the original on 2008-01-15 . Retrieved . CS1 maint: BOT: original-url status unknown ( link)
Fairbridge, Rhodes W. (1961). "Eustatic Changes in Sea Level". Physics and Chemistry of the Earth. 4: 99-185. Bibcode: 1961PCE.....4...99F. doi: 10.1016/0079-1946(61)90004-0.
Murray-Wallace, Colin; Woodroffe, Colin (2014). . Cambridge University Press. p. 338. Quaternary Sea-Level Changes: A Global Perspective
Thompson, L. G.; Mosley-Thompson, E.; Brecher, H.; Davis, M.; León, B.; Les, D.; Lin, P. -N.; Mashiotta, T.; Mountain, K. (2006). "Inaugural Article: Abrupt tropical climate change: Past and present". Proceedings of the National Academy of Sciences. 103 (28): 10536-10543. Bibcode: 2006PNAS..10310536T. doi: 10.1073/pnas.0603900103. PMC . 1484420 PMID 16815970.
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Dershowitz, Nachum; Reingold, Edward M. (1997), Calendrical Calculations (1st ed.), Cambridge University Press, p. 11, ISBN 978-0-521-56474-8