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.
School of Naturalists and Qi. In later periods, these epistemological theories came to hold significance in both philosophy and popular belief. This school was absorbed into the alchemic and magical dimensions of Taoism as well as into the Chinese medical framework. The earliest surviving recordings of this are in the Ma Wang Dui texts and Huang Di Nei Jing. Zou Yan (; 305240 BC) was an ancient Chinese philosopher best known as the representative thinker of the Yin and Yang School (or School of Naturalists) during the Hundred Schools of Thought era in Chinese philosophy. Zou Yan was a noted scholar of the