Neanderthal were archaic humans - they became extinct about 40,000 years ago after interbreeding with modern humans. Appearing in Europe and West Asia, they expanded into Southwest, Central and Northern Asia. There were possibly three separate episodes of interbreeding; one soon after leaving Africa; another after the ancestral Melanesians had developed into a different group and would go on to breed with Denisovans; then a later third interbreeding with East Asians. There is some speculation that Neanderthals may have used simple boats to cross water.