questions on human race

I was watching a show on the history channel and they were discussing the Neanterdal and the Cromagons - that is the beginings of modern man. It seems like the Neantersal died out 15000 years ago,I think they said and the Cromadian just came to Europe. about 50 thousand years ago.It all seems so strange as the Clovis Indians came to North America abvout 12000 bce to 15000.I know I am putting together wrong but the People came to Australian continient about 50,000 years ago.It intrigueing to me to try and put all these dates together.Why dan not these Scientist put together a Time line putting together all these imigration factors.Did not these Neanterthals last at least 250,000 year or I have read the wrong stuff. I took a course at WSU and even in that course there were not any times line. There are so many factors that never seems to be put together to make sense. It seems like there were some Indiaan camp sights in Chile and I think in what is now Virginia that supposedly go back abou 20,000 years ago. These are interesting ideas that would when put together sure make some history books not so accurate.Everything in learning is so piece meal that I think they miss the true facts of the picture.I thought it might be an interesting thought to try put Ideas together. Oh well I reminds me of a Radar set that I worked on and to get to the poing -they broke the set down into individual cabinets that all work perfectly but the Radar set never really worked. The people overlooked the fact that one pulse led into another and either added or substracted from the function of how the unit was supposed to work. Feedback is a glorius thought to work with. Anyway with everything broken down into to small pieces how any knowleldge ever put together. I could just go on but I am just rambling and I am trying to stay on the subject. There are constant questions that I never seem to get answers to.The more I read or watch shows like the History channes the more the questions seem to come out. Don