Taijitu seen in Tripilja culture in Ukraine, displayed in the Ukraine pavilion at the Expo 2010 in Shanghai, China. Also, the interlocking design is found in artifacts of the European Iron Age. While this design appears to become a standard ornamental motif in Iron-Age Celtic culture by the 3rd century BC, found on a wide variety of artifacts, it is not clear what symbolic value was attached to it. Unlike the Chinese symbol, the Celtic yin-yang lack the element of mutual penetration, and the two halves are not always portrayed in different colors. Comparable designs are also found in Etruscan art.
Taijitu has its nature. Instead of usual "Taiji" translations "Supreme Ultimate" or "Supreme Pole", Adler uses "Supreme Polarity" (see Robinet 1990) because Zhu Xi describes it as the alternating principle of "yin" and "yang", and ... insists that "taiji" is not a thing (hence "Supreme Pole" will not do). Thus, for both Zhou and Zhu, "taiji" is the "yin-yang" principle of bipolarity, which is the most fundamental ordering principle, the cosmic "first principle." "Wuji" as "non-polar" follows from this. Since the 12th century, there has been a vigorous discussion in Chinese philosophy regarding the ultimate origin of Zhou Dunyi's diagram. Zhu