I never understood this statement about the color blue like it has been claimed that ancient cultures may not have known it because they were not able to reprod

I never understood this statement about the color blue like it has been claimed that ancient cultures may not have known it because they were not able to reproduce it and therefore were not able to knowingly see it. It reads nonsense to me as the sky is blue. It is a good example but I think describing sensory experience is not that difficult or impossible, for example I have never tried cocaine, regardless I have pretty good idea what it might feel like. But imagine if your language lacks some grammatical concepts like future.