We know that there was at least some overlap between modern humans and neanderthals in western Europe around 40,000 years ago, but that the Neanderthals eventually were replaced or assimilated. However, there is strong evidence of the existence of a Neanderthal refuge in in the region of modern-day Spain and Portugal for several thousand years after they had vanished from the rest of Europe. What has been uncertain is exactly how long these populations persisted, and what ultimately became of them. Science Daily reports on new research by Joao Zilhao and his team which indicates that modern humans were established in the region by 37,000 years ago, suggesting that the Neanderthal refuge had declined by that time. This means that the Neanderthals persisted in the region for only about 5,000 years, considerably less than the 15,000 or so that had been previously suggested.

There's another interesting implication of this find. A 30,000 year old fossil find of a chlid in Portugal demonstrates some previous features, and there have been some rather off-the-wall suggestions that this might be evidence of hybridization between a relict Neanderthal population and modern humans. Doesn't look like the new time frame allows for that possibility.