World Peace Association's proposed flag representing all humanity.  Their description from 1938:
"The Brotherhood Flag consists of five (5) horizontal stripes of equal width. The first or top strip is red the second stripe is white, the third stripe is brown, the fourth strip is yellow and the fifth or bottom stripe is black. Each stripe represents one of the five different groups of the human race."
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<span class="int-own-work" lang="en">Own work</span>