Editing Watermill (section)

===Ancient East Asia===
[[Image:Song Dynasty Hydraulic Mill for Grain.JPG|thumb|right|A [[Song dynasty|Northern Song era]] (960&ndash;1127) water-powered mill for dehusking grain with a horizontal wheel]]

The waterwheel was found in China from 30 AD onwards, when it was used to power [[trip hammer]]s,<ref>Needham (1986), Volume 4, Part 2, pp.&nbsp;390&ndash;392</ref> the [[bellows]] in [[History of ferrous metallurgy|smelting iron]],<ref>{{harvnb|de Crespigny|2007|p=184}}</ref><ref>Needham (1986), Volume 4, Part 2, 370.</ref> and in one case, to mechanically rotate an [[armillary sphere]] for [[Chinese astronomy|astronomical observation]] (see [[Zhang Heng]]).<ref>{{harvnb|de Crespigny|2007|p=1050}}</ref><ref>Needham (1986), Volume 4, Part 2, 88&ndash;89.</ref> Although the British chemist and sinologist [[Joseph Needham]] speculates that the water-powered millstone could have existed in Han China by the 1st century AD, there is no sufficient literary evidence for it until the 5th century AD.<ref>Needham (1986), Volume 4, Part 2, 396&ndash;400.</ref> In 488 AD, the mathematician and engineer [[Zu Chongzhi]] had a watermill erected which was inspected by [[Emperor Wu of Southern Qi]] (r. 482&ndash;493 AD).<ref name="needham 1986 volume 4 part 2 400" >Needham (1986), Volume 4, Part 2, 400.</ref> The engineer Yang Su of the [[Sui dynasty]] (581&ndash;618 AD) was said to operate hundreds of them by the beginning of the 6th century.<ref name="needham 1986 volume 4 part 2 400" /> A source written in 612 AD mentions [[Bhikkhu|Buddhist monks]] arguing over the revenues gained from watermills.<ref>Needham (1986), Volume 4, Part 2, 400&ndash;401.</ref> The [[Tang dynasty]] (618&ndash;907 AD) 'Ordinances of the Department of Waterways' written in 737 AD stated that watermills should not interrupt riverine transport and in some cases were restricted to use in certain seasons of the year.<ref name="needham 1986 volume 4 part 2 400"/> From other Tang-era sources of the 8th century, it is known that these ordinances were taken very seriously, as the government demolished many watermills owned by great families, merchants, and [[Chinese Buddhism|Buddhist abbeys]] that failed to acknowledge ordinances or meet government regulations.<ref name="needham 1986 volume 4 part 2 400"/> A [[Eunuch (court official)|eunuch]] serving [[Emperor Xuanzong of Tang]] (r. 712&ndash;756 AD) owned a watermill by 748 AD which employed five waterwheels that ground 300 [[bushel]]s of wheat a day.<ref name="needham 1986 volume 4 part 2 400" /> By 610 or 670 AD, the watermill was introduced to [[Japan]] via [[Korean Peninsula]].<ref name="needham 1986 volume 4 part 2 401" >Needham (1986), Volume 4, Part 2, 401.</ref> It also became known in [[Tibet]] by at least 641 AD.<ref name="needham 1986 volume 4 part 2 401"/>