Why the Climate change should gradually reverse towards the end of the 5th century?? The same Climate change stayed till the 8th century at least.It doesnt make sence.One of the not known reasons for the Arab expansion in the 7th century with the Rise of Islam was the climate became more drier For example North Africa became a dry coastline with no vegitation compared with the 3rd-4th century and still is to the present day.Untill then it was the Breadbacket of the Roman Empire together with Egypt