Editing 3rd century BC (section)

==Inventions, discoveries, introductions==
*[[Eratosthenes]] accurately calculates [[Earth's circumference]] and introduces the [[sieve of Eratosthenes]], an algorithm for identifying [[prime number]]s.
*[[Go (board game)|Weiqi]], known as Go in English, well-established in [[China]], and may date back to the [[2nd millennium BC]].
*[[Crucible steel]] was first produced in Southern [[India]].
*Canopus stele of [[Ptolemy III]] implements the [[leap year]] in Egypt. Leap year not formally recognized until Caesar in 55 BC.
*First Roman [[sundial]] (293 BC).<ref>Pliny ''Natural History'' 7.213</ref>
*[[Toe stirrup]] finds its earliest manifestation in [[India]].
*[[Archimedes' screw|Water screw]] invented by [[Archimedes]].
*The [[Euclidean algorithm]], the oldest algorithm still in use today, introduced by [[Euclid]].
*Invention of the [[hydraulis]] (the precursor to the [[Pipe organ]]) by [[Ctesibius]], a Greek engineer working in [[Alexandria]].
*[[Zinc mining]] was first smelted from zinc ore in [[India]]
*[[Emperor Gaozu of Han]] China discovers an elaborate [[Ma Jun (mechanical engineer)#Engineering and technological achievements|mechanical puppet theater]] in the treasury of the previous ruler [[Qin Shi Huang]].
*The enormous [[Du Jiang Yan Irrigation System]] of China is engineered and constructed by [[Li Bing (Qin)|Li Bing]] (李冰) in [[256 BC]].
*Great Stupa, [[Sanchi]], [[Madhya Pradesh]], [[India]], [[Maurya period]], is founded by King [[Chandragupta Maurya]].
*[[Silk]] is exported to [[Europe]] from China.
*[[Armillary sphere]]s, models of objects in the sky developed by the Greeks, are in use as teaching tools.
*[[Rotary mill]] invented by the ancient Greeks.<ref>{{cite journal |last1=Yannopoulos |first1=Stavros |last2=Lyberatos |first2=Gerasimos |last3=Theodossiou |first3=Nicolaos |last4=Li |first4=Wang |last5=Valipour |first5=Mohammad |last6=Tamburrino |first6=Aldo|author7-link=Andreas N. Angelakis |last7=Angelakis |first7=Andreas |title=Evolution of Water Lifting Devices (Pumps) over the Centuries Worldwide |journal=Water |date=2015 |volume=7 |issue=9 |pages=5031–5060 |doi=10.3390/w7095031 |doi-access=free |bibcode=2015Water...7.5031Y }}</ref>