In 1992, some Egyptian mummies were being examined by German scientists, when they found remnants of tobacco, hashish and cocaine in the desiccated remains. To begin with, the discovery didn't seem all that terrible, who are we to tell Ancient Egyptians how to live their lives, after all? However, it was later realised that neither cocaine nor tobacco were supposed to be around back then. They were supposed to be safely contained in a Pre-Columbian America, where Native Americans were presumably having a wail of a time. The cocaine mummies were considered to be contaminated, a hoax or just a straight-up "mystery", and the very best minds puzzled over it. Many thought that the scientists had been carelessly smoking whilst carrying out test on the mummies and had contaminated them that way. There are even some corners of the internet that put forward the idea that ancient aliens (always with the ancient aliens) were providing some kind of narcotic courier service between continents. A lot of this seems to be skirting over the possibility that maybe, just maybe, ancient travellers might have gotten to America before Columbus accidentally crashed his ship into it. No need to even imagine ancient Egyptians sailing cross the vast Atlantic in their papyrus boats either, just look at the map from this perspective and the Americas don't look all that far away after all.
