Maybe your misunderstanding me, I did give certain groups such as Native American's & Aborigines(both that are still here in the 21 century) most Asian countries still have deep roots. I would make it a point that if they traveled to our present.....as mentioned we have folks travel to the past, we have people travel to what we would consider our future. What we don't have are people from the past traveling to our present. We can go off on tangents discussing, future technologies making time travel possible..........but, putting it bluntly were still talking about theory(transporter beam or magic gates). Point that I'm making is you can research older ways...that's history....you can't with the future, it's an unknown.........and we do live in the present. Examples of what I'm talking about: 18 century folk traveling to either the 20th or 21st century, 16 century folk traveling to 20th/21st century, 19th>>>>>>>>>>>20/21 century. It doesn't have to be cavemen like Encino man. As many cultures flourished and gone(like the Mayans, Huns, Romans, peoples of Europe like vikings, Gauls, Celts, North American tribes, Egypt or Israel or Pacific island natives...China, Japan)you could even have people from the early 20th century come to the present. Getting to the present doesn't have to be difficult(no much more difficult the tech that we don't have or has been dreamed up that we expect in the future). Tech like cryo(Encino man, the thing, Avatar,and Futurrama), magic portals(the gate, anything with a worm hole)might lay in the future. A magic portal or gateway isn't discounted in the future, so why wouldn't possible in the past(under a certain set of circumstances).........along the lines of the Philadelphia experiment....or someone finding H.G.Wells time machine....or factors like a lightning strike combined with a rock formation. Thing you will always see folks go from modern day to the past............or modern day to future or another planet or other dimension/world. All I going on is bringing people with lost skills into the present(wouldn't be curious if there was a cure for something, or treatment that was lost.....but would be effective on modern illnesses......but only that ancient knowledge holds the key[watch the movie "the Medicine Man"]..............then if people want they can inject what every they deem the amount of erotic stuff they want.