Flag of the Mahdi movement in Sudan, late 19th century.
<a href="//commons.wikimedia.org/wiki/User:Samhanin" title="User:Samhanin">Samhanin</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>, source: <a rel="nofollow" class="external text" href="https://www.britishmuseum.org/research/collection_online/collection_object_details/collection_image_gallery.aspx?partid=1&amp;assetid=1462120001&amp;objectid=587576">The British Museum</a>