Young Red Haired Girl Portrait

The Chinese characters for ang mo are the same as those in the historical Japanese term Kōmō (紅毛), which was used during the Edo period (1603–1868) as an epithet for (northwestern European) white people. It primarily referred to Dutch traders who were the only Europeans allowed to trade with Japan during Sakoku, its 200-year period of isolation.
Religious and mythological traditions
Red is the preferred dyeing color in Islam. It is said that Muhammad used to dye his hair red using Henna. Henna or Hina is a flowering plant which traditionally has been used to dye hair red. There are no side effects to this. Al-Bukhari related in his Sahih, from 'Uthman b. 'Abd-Allah b. Mawhab: "We went to Umm Salma, and she brought out for us some of the hair of the Messenger of Allah, and lo, it was dyed with henna and indigo." (Bukhari, Libas, 66) And in the four sunan, it is related that he said, "The best you can use for changing the color of white hair are henna and katam." (Tirmidhi, Libas, 20). In the two books of the Sahih, from Anas, it is quoted that Abu Bakr used hair dye of both henna and katam. (Muslim, Fada’il, 100) (Ibn Qayyim; 259) (Katam is a plant from Yemen which produces a reddish-black dye).