Maybe flags beside the altar are an evolution of earlier symbols such as staffs (Aaron's rod placed before / inside the Ark of the Covenant); also, what were "horns" of the altar in the Hebrew Bible? Does anyone know what are the 'wooden asherah poles' placed before Yahweh's altar and considered idolatrous by the biblical authors (many references on Biblegateway (NIV)). Are these asherah a sort of staff (rod) or maybe young trees as in the Tree of Life, Her sacred tree? At Stonehenge there are upright stones not part of the circle but within it, likewise there are uprights in the Göbekli Tepe circles in Turkey built thousands of years before Stonehenge, if I recall correctly. Likewise the upright poles arranged around the stone circles in Bruniquel Cave in France, constructed approximately 176,500 years ago by Neanderthals, it is claimed. Symbols such as poles, uprights, candles, (maybe a candle is just a candle, hehehe), have their history. But maybe a flag is just a flag.