It is interesting to consider how much of an effect that weather and environmental conditions can have on a society and its way of life. The Neolithic Sub Pluvial (or Wet Holocene) was an extended period of time characterized by a wet and rainy climate. Because of this, Neolithic populations were able to inhabit areas of the Western Desert that today are as dry as bones. However, near the end of this period the rains began to move southward leaving the desert dessicated. As a result, the existing populations left and began to inhabit the Nile Valley which laid the basis for Upper Egypt. The basis for Lower Egypt came from Fayum Neolithic populations.
This period of time formed the foundation for the separation between Upper and Lower Egypt. But to think, what if the rains had not shifted until much later,or if the populations had followed the rains south instead of moving toward the Nile? The entire timeline of ancient Egyptian culture would have been completely different. This transition was obviously not quick but happened over a period of time, but it is a small section of time that was absolutely crucial to that portion of the world as it is known today.
Even though on a larger scale, it makes me think of the Ice Age. That was also a period of time that was characterized by the climactic conditions and shaped the way in which our world existed thereafter.
There is this idea known as North African climate cycles which is dependent on the North African Monsoon. “When the North African Monsoon is at its strongest annual precipitation and subsequent vegetation in the Sahara region increase, resulting in conditions commonly referred to as the green Sahara. For a relatively weak North African Monsoon the opposite is true, with decreased annual precipitation and less vegetation resulting in a phase of the Sahara climate cycle known as the desert Sahara.”