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 * 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 * 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.