“the only viable counterargument is that the earlier coat of paint that, long before, had built megalithic monuments such as Stonehenge, was trampled to death by the later wave of migrants”
They didn’t have math or the written word.
They tramplers had the written word, although it’s often denied. If the megalith builders had writing, they either used fragile materials which haven’t survived, or they painted it on surfaces and it has washed away, and/or isn’t visible without special technology now.