Wikipedia
A taijitu ( Traditional Chinese: ; Simplified Chinese: ; Pinyin: tàijítú; Wade-Giles: t'ai⁴chi²t'u²), also called monad, is a symbol or diagram ( tú) in Chinese philosophy representing Taiji ( tàijí "great pole" or "supreme ultimate") representing both its monist ( wuji) and its dualist ( yin and yang) aspects. Such a diagram was first introduced by Song Dynasty Zhou Dunyi (周敦頤 1017–1073) in his the Taijitu shuo .
The modern Daoist canon, compiled during the Ming era, has at least half a dozen variants of such taijitu. The two most similar are the "Taiji Primal Heaven" (太極先天圖 tàijí xiāntiān tú) and the " wuji" (無極圖 wújí tú) diagrams, both of which have been extensively studied during the Qing period for their possible connection with Zhou Dunyi's taijitu.
Ming period author Lai Zhide (1525–1604) simplified the taijitu to a design of two interlocking spirals. In the Ming era, the combination of the two interlocking spirals of the taijitu with two black-and-white dots superimposed on them became identified with the He tu or "Yellow River diagram" (河圖). It is this version that has been widely popularised as the "yin-yang symbol" in the West since the 1960s. The contemporary Chinese term for the modern symbol is "two-part Taiji diagram".
Unicode features the "yin-yang symbol" in the Miscellaneous Symbols block, at code point U+262F (YIN YANG ☯). The related "double body symbol" is included at U+0FCA (TIBETAN SYMBOL NOR BU NYIS -KHYIL ࿊), in the Tibetan block.
Ornamental patterns with visual similarity to the "yin-yang symbol" are found in archaeological artefacts of European prehistory; such designs are sometimes descriptively dubbed "yin yang symbols" in archaeological literature by modern scholars.