Before the advent of Islam, banners as tools for signaling had already been employed by the pre-Islamic Arab tribes and the Byzantines. Early Muslim army naturally deployed banners for the same purpose. Early Islamic flag, however, greatly simplified its design by using plain color, due to the Islamic prescriptions on aniconism. According to the Islamic traditions, the Quraysh had a black ' and a white-and-black '. It further states that Muhammad had an ' in white nicknamed "the Young Eagle" ( '); and a "" in black, said to be made from his wife Aisha's head-cloth. This larger flag was known as " the Banner of the Eagle" ( "al-rāyat al-ʻuqāb"), as well as "the Black Banner" ( "ar-rāyat as-sawdāʾ"). Other examples are the prominent Arab military commander 'Amr ibn al-'As using red banner, and the Khawarij rebels using red banner as well. Banners of the early Muslim army in general, however, employed a variety of colors, both singly and in combination.