Shia Muslim flags usually include the color green in them, which is a symbol of Islam, and also a symbol of purity, fertility and peace. Common colors in Shia Muslims flags are red, white and green; common symbols include the Lion and Sun, the Zulfiqar and the Shahada.
The Fatimid dynastic color was white, in opposition to Abbasid black, while red and yellow banners were associated with the Fatimid caliph's person.[1][2][3]
^Blair, Sheila S.; Bloom, Jonathan M. (1999). "Art and Architecture: Themes and Variations". In Esposito, John L. (ed.). The Oxford History of Islam. Oxford: Oxford University Press. pp. 215–267. ISBN0-19-510799-3. ...white was also the color associated with the Fatimid caliphs, the opponents of the Abbasids.
^Sanders, Paula A. (1994). Ritual, Politics, and the City in Fatimid Cairo. SUNY series in Medieval Middle East History. SUNY Press. p. 44. ISBN0-7914-1781-6. ...wore white (the Fatimid color) while delivering the sermon (khuṭba) in the name of the Fatimid caliph.