Taijitu the Tibetan designs have three or four swirls (representing the Three Jewels or the Four Noble Truths, i.e. as a triskele and a tetraskelion design), Lai Zhide's taijitu has two swirls, terminating in a central circle. The Ming-era design of the taijitu of two interlocking spirals has been reported as "yin-yang symbol" in the first half of the 20th century. The flag of South Korea, originally introduced as the flag of Joseon era Korea in 1882, shows this symbol in red and blue. This was a modernisation of the older (early 19th century) form of the Bat Quai Do used
Yin and yang light; female and male; moon and sun", however, is an exception. Scholars have proposed various explanations for why "yinyang" violates this pattern, including "linguistic convenience" (it is easier to say "yinyang" than "yangyin"), the idea that "proto-Chinese society was matriarchal", or perhaps, since "yinyang" first became prominent during the late Warring States period, this term was "purposely directed at challenging persistent cultural assumptions". Needham discusses Yin and Yang together with Five Elements as part of the School of Naturalists. He says that it would be proper to begin with Yin and Yang before Five Elements because the former: "lay, as