1st century

== Inventions, discoveries, introductions ==
{{See also|Timeline of historic inventions#1st century}}
* [[Codex]], the first form of the modern book, appears in the Roman Empire.{{Citation needed|date=August 2022}}
* Various inventions by [[Hero of Alexandria]], including the [[steam turbine]] (aeolipile), [[water organ]], and various other water-powered machines.
* c. [[AD 23]]: the Chinese astronomer [[Liu Xin (scholar)|Liu Xin]] dies, he documented 1080 different stars, amongst other achievements.
* [[AD 31]]: the [[Han dynasty]] Chinese engineer and statesman [[Du Shi]] (d. [[AD 38]]) from [[Nanyang, Henan|Nanyang]] invented the first-known [[hydraulic]]-powered [[bellows]] to heat the [[blast furnace]] in smelting [[cast iron]]. He used a complex mechanical device that was powered by the rushing current against a [[waterwheel]], a practice that would continue in China.
* [[AD 78]]: the beginning of the Saka Era used by South Asian calendars.
* c. [[AD 80]]: although [[Philo of Byzantium]] described the saqiya [[chain pump]] in the early 2nd century BC, the square-pallet [[chain pump]] was innovated in China during this century, mentioned first by the philosopher [[Wang Chong]] around AD 80. Wang Chong also accurately described the [[water cycle]] in [[meteorology]], and argued against the mainstream 'radiating influence' theory for [[solar eclipse]]s, the latter of which was accepted by many, including [[Zhang Heng]].