Whilst you are waiting for an answer you can read some earlier threads on here. In this answer u/EphemerealBlue writes about how the tricolour spread from France, to the rest of Europe and the world. And here you can read about flags and banners on Mediaeval ships, as written by u/jschooltiger. There are also threads about how flags were used differently and what was used instead of national flags, in Ancient Rome (by u/toldinstone), in pre-Qing China (by u/cthulhushrugged) and in the indigenous American Southeast (by u/Milkhemet_Melekh). Further answers by our users are of course appreciated