Bradshaw foundation has created an interesting flash video depicting journey of the human race. It looks at the way human population has spread from its early origins (150K years ago) to 6000 BC.

It is interesting to note that civilization in India is pretty old dating back to 80,000 years. But it was almost completely wiped of by the eruption of Mt. Toba around 74,000 years ago (probably reducing the population to as low as 10,000!!)

Yes, this may not be 100% accurate, but is backed up with the data we have so far.