The Sinian Period is the third period of the Neoproterozoic Era in China. It extended from 680 million to 542 million years ago, a duration of 138 million years, and is equivalent to the international Ediacaran Period. The Sinian System includes the rocks that formed during the Sinian Period. The standard section of the system is located in the Three Gorges area. The term ‘Sinian’ originates from the nomenclature in ancient China (Latin Sina). It was first used as a stratigraphic term by Richthofen in 1871. Its initial meaning refers to the large body of carbonate rocks that were deposited on top of an ancient metamorphic rock system.