4200 B.C.E.
* Celestial North makes closest approach to theta Bootis
* Sumerians using a sidereal calendar (accurate to within ten seconds)
* Sumer first to have potters' wheels, wheeled transports, woven textiles
  and copper articles: spearheads, arrows & quivers
  <www.copper.org/education/history/60centuries/ancient/thesumerians.htm>
* Technological use of bitumens & asphalts begins in Sumer, leading to the
  use of kilns to smelt metallic ores, and to make alloys, such as bronze
* Divine-right kingship begins in Kish

* Bronze Age civilisation develops along Indus & Ghaggar-Hakra
  (Sindhu & Sarasvati) River valleys at Mohan-Jo-Daro, Harappa etc.
* 27 sidereal stations of the moon described in Rgvedic astrology, later
  to be adopted by the Druids for their 27-day lunar month      
  [Kak, Birth and Development of Indian Astronomy.]
* Horses are domesticated on southern Russia's steppes.
* Domestication of the Arabian camel--vital for traversing hot, arid areas
  <www.hiviewfarms.com/livenativ.htm>
* Chalcolithic Longshan/Yangshao culture begins along Yellow River valley
* Egyptians use stick figures for numbers
* Minoan civilisation starts, records first use of the decimal symbols for
  whole numbers, and is the first to depend on maritime trading

  3300 B.C.E.
* Egyptian reference to the vernal equinox being in Taurus when winter
  solstice coincided with acronycal rising of Sirius (3285)
* Vriddha/Old Aryabhata describes a geocentric model of the solar system:
  moon & sun each move on a circle; motions of each planet governed by
  two circles; Mercury & Venus on a smaller fast circle moving along a
  larger slow circle; positions calculated relative to epicentres moving
  uniformly around the earth in the same manner as for the sun; in the
  case of Mars, Jupiter & Saturn, they move around the earth at specific
  speeds representing each planet's motion through the zodiac; his model
  formulates elements of Greek astronomy pre-Ptolemaeus/Romaka-Siddhanta,
  and even uses a 365-day year as did Ptolemaeus
  [(Vriddh)Aryabhata-Siddhanta.]
* Epoch of Surya-Sunu & Yudhisthira Eras (3188)
* Mahabharata War (3162)
* Epoch of the Mayan Long Count calendar  (Monday 6 September 3114)
* The current Kali Yuga begins when the sun, the moon, and five naked-eye
  planets appear between Asvini & Revati  (Friday 18 February 3101 O.S.)
* Stele of Serpent King in Egypt's Middle Kingdom style shows the falcon's
  profile of Horus in bas-relief above the stroke for a snake 
  [Stela of Djet, Louvre]
* First phonetic writing system in the West, cuneiform, formalised by the
  Sumerians for their language, as well as for that of the Akkadians
* Elamites develop their own version of cuneiform
  2800 B.C.E.