Tang of Shang
"Although many ancient cultures believed rainbows were good omens,"Carr explains, "the Chinese saw them as meteorological disasters. Unlike the auspicious ["long"] dragon symbolizing forthcoming rain, the two-headed ["hong"] was inauspicious because it appeared after a rain shower." The "Huainanzi" says both rainbows and comets were warnings from "tian" "heaven; god". Several classic texts (e.g., Liu Xiang's "Shuoyuan" and "Xinxu") use the phrase "baihong guan ri" "bright rainbow threads the sun". For example, it is a portent of assassination in the "Zhanguoce" "a white halo pierced the sun." One notable exception is the "Mengzi" using "yunni" "cloud and rainbow" to describe the legendary Tang of Shang: "the people looked to him, as we look in a time of great drought to the clouds and rainbows."