Newly discovered stone artifacts that suggest humanity left Africa through the Arabian Peninsula could re-write early human history.

More than 100 stone tools discovered in Oman showed that early humans were already living in southern Arabia much earlier than scientists had thought. Modern humans had first lived in Africa over 200,000 years ago but scientists believe that they didn't migrate worldwide until 40,000 to 70,000 years ago. The new study by an international team of researchers, show that the stone artifacts are at least 100,000 years old, which could blow that long believed theory out of the water.

"After a decade of searching in southern Arabia for some clue that might help us understand early human expansion, at long last we've found the smoking gun of their exit from Africa," said lead researcher Jeffrey Rose, a paleolithic archaeologist at the University of Birmingham in England.

"What makes this so exciting is that the answer is a scenario almost never considered."

The Out of Africa model of human expansion states that modern humans evolved in Africa and migrated outwards following the coast of Arabia. Geneticists usually peg this expansion between 40,000 and 70,000 years ago. Previous theories had suggested that early humans followed the Arabian coastline but the discoveries of stone artifacts inland could throw this idea into question.

The researchers used a technique called Optically Stimulated Luminescence that measures that amount of light objects can emit to see how long they have been buried. The researchers dated the stone artifacts to around 106,000 years old, too early for the timeframe of the exodus from Africa.

The geological record shows that Arabia was a much wetter place with frequent rainfall that transformed its landscape to sprawling grasslands with plenty of resources for early humans to subsist on.

"For a while South Arabia became a verdant paradise rich in resources - large game, plentiful freshwater, and high-quality flint with which to make stone tools," said Rose in the release.

The researchers doubt the stone tools were created by other human species like the Neanderthals. All the Middle Stone Age tools seen in Africa were associated with modern human ancestors.

The scientists published their findings online on November 30 in the journal PLoS ONE.