The 4th millennium BC saw major changes in human culture. It marked the beginning of the Bronze Age and of writing.

The city states of Sumer and the kingdom of Egypt were started and grew to prominence. Agriculture spread widely across Eurasia. World population in the course of the millennium doubled to approximately from 7 to 14 million people in the area surrounding them.

Events
Mesopotamia is in 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.
c. 4000 BC—First neolithic settlers in the island of Thera (Santorini), Greece, migrating probably from Minoan Crete.
c. 4000 BC—Beaker from Susa (modern Shush, Iran) is made. It is now at Musée du Louvre, Paris.
c. 4000 BC–2000 BC—People and animals, a detail of rock-shelter painting in Cogul, Lleida, Spain, are painted. It is now at Museo Arqueológico, Barcelona.
c. 3900 BC—5.9 kiloyear event, one of the most intense aridification events during the Holocene. It ended the Neolithic Subpluvial and likely initiated the most recent desiccation of the Sahara desert, triggering migration to river valleys, such as from central North Africa to the Nile valley.
Babylonian influence predominant in Mediterranean regions of Asia (to 2000 BC)
In Colombia, circa 3600 BC, first rupestrian art Chiribiquete (Caquetá).
3600 BC—Construction of the Ġgantija megalithic temple complex on the Island of Gozo, Malta: 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 on Malta, containing "furniture" such as stone benches and tables, that set it apart from other European megalith constructions.
3600–3000 BC—Construction of the Ta' Ħaġrat and Kordin III temples on Malta.
3500 Metalcasting began in the Mohenjodaro area.
c. 3500 BC—Figures of a man and a woman, from Cernavodă, Romania, are made. They are now at National Historical Museum, Bucharest.
3500–3400 BC—Jar with boat designs, from Hierakonpolis (today in the Brooklyn Museum) is created. Predynastic Egypt.
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.
3300–2900 BC—Construction of the Newgrange solar observatory/passage tomb in Ireland.
 3300—Bronze Age starts in Indus Valley (Harappa)
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.
3250–3000 BC—Construction of three megalithic temples at Tarxien, Malta.
3200–2500 BC—Construction of the Ħaġar Qim megalithic temple complex on Malta, featuring both solar and lunar alignments.
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. 3150 BC a lesser Tollmann's hypothetical bolide event may have occurred.
 August 11, 3114 BC—start date of the Mayan calendar.
c. 3100 BC—According to the legend, Menes unifies Upper and Lower Egypt, and a new capital is erected at Memphis.
c. 3100 BC—Narmer Palette
c. 3100–2600 BC—Neolithic settlement at Skara Brae in the Orkney Islands, Scotland, is inhabited.
First to Fourth dynasty of Kish in Mesopotamia.
Discovery of silver.
The beginnings of Iberian civilizations, arrival to the peninsula dating as far back as 4000 BC.
c. 3000 BC—First pottery in Colombia at Puerto Hormiga (Magdalena), considered one of the first attempts of pottery of the New World. First settlement at Puerto Badel (Bolívar).
Sumerian temple of Janna at Eridu erected.
Temple at Al-Ubaid and tome of Mes-Kalam-Dug built near Ur, Chaldea.

Significant persons
 Ötzi the Iceman lived c. 3300 BC.
 Predynastic pharaohs, Tiu, Thesh, Hsekiu, Wazner
 Early Dynastic Period pharaohs, Ro, Serket, Narmer

Inventions, discoveries, introductions

c. 4000 BC—potter's wheel in Sumer.
4000 BC—Susa is a center of pottery production.
c. 4000 BC—Horses are domesticated in Ukraine.
3500 BC—2340 BC; Sumer: wheeled carts, potter's wheel, White Temple ziggurat, bronze tools and weapons.
c. 3250 BC—potter's wheel appears in Ancient Near East.
3000 BC—Tin is in use in Mesopotamia soon after this time.
Beginnings of urbanisation in Mesopotamia in Sumer and Egypt.
First writings in the cities of Uruk and Susa (cuneiform writings). Hieroglyphs in Egypt.
Kurgan culture of what is now Southern Russia and Ukraine; possibly the first domestication of the horse.
Sails used in the Nile.
Construction in England of the Sweet Track, the World's first known engineered roadway.
Drainage and Sewage collection and disposal created in the Indus Valley civilization.
Dams, canals, stone sculptures using inclined plane and lever in Sumer.
Copper was in use, both as tools and weapons.
Bronze was in use, specifically by the Maykop culture.
Mastabas, the predecessors of the Egyptian pyramids.
The earliest phase of the Stonehenge monument (a circular earth bank and ditch) dates to c. 3100 BC.
The Céide Fields in Ireland, arguably the oldest field system in world, are developed.
Sumerian writing, done on clay tablets, shows about 2,000 pictographic signs.
White painted pottery in Egypt and southeastern Europe.
Harps and flutes played in Egypt.
Copper alloys used by Egyptians and Sumerians; smelting of gold and silver known.
Lyres and double clarinets (arghul, mijwiz) played in Egypt.
Earliest known numerals in Egypt.
Linen is produced in the Middle East.

Religion
 Sri Krishna and Mahabharata.
 Adam, Cain, Enoch, Methuselah, and Noah.

Calendars and chronology
The Maya calendar dates the creation of the Earth to August 11 or August 13, 3114 BC (establishing that date as day zero of the Long Count 13.0.0.0.0).
According to calculations of Aryabhata (6th century), the Hindu Kali Yuga began at midnight (00:00) on 18 February 3102 BC. Consequently, Aryabhata dates the events of the Mahabharata to around 3137 BC.
7 October 3761 BC—Epoch of the Hebrew Calendar (introduced in the 12th century).
3929 BC—Date of creation according to John Lightfoot based on the Old Testament of the Bible, and often associated with the Ussher chronology.
1 January 4000 BC — Epoch of the Masonic calendar's Anno Lucis era.

Centuries
 40th century BC
 39th century BC
 38th century BC
 37th century BC
 36th century BC
 35th century BC
 34th century BC
 33rd century BC
 32nd century BC
 31st century BC

References