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 "to shelter; shade", and 陽 or 阳 "sunny" is always pronounced with rising second tone "yáng". Sinologists and historical linguists have reconstructed Middle Chinese pronunciations from data in the (7th century CE) "Qieyun" rhyme dictionary and later rhyme tables, which was subsequently used to reconstruct Old Chinese phonology from rhymes in the (11th-7th centuries BCE) "Shijing" and phonological components of Chinese characters. Reconstructions of Old Chinese have illuminated the etymology of modern Chinese words. Compare these Middle Chinese and Old Chinese (with asterisk) reconstructions of "yīn" 陰 and "yáng" 陽: Schuessler gives probable Sino-Tibetan etymologies for both Chinese words. "Yin"