The earliest mention of ammonium chloride was in 554 A.D. in China. At that time, ammonium chloride came from two sources: (1) the vents of underground coal fires in Central Asia, specifically, in the Tian Shan mountains (which extend from Xinjiang province of northwestern China through Kyrgyzstan) as well as in the Alay (or Alai) mountains of southwestern Kyrgyzstan, and (2) the fumaroles of the volcano Mount Taftan in southeastern Iran. (Indeed, the word for ammonium chloride in several Asian languages derives from the Iranian phrase anosh adur (immortal fire), a reference to the underground fires.) Ammonium chloride was then transported along the Silk Road eastwards to China and westwards to the Muslim lands and Europe.