When the Sea Saved Humanity

https://www.scientificamerican.com/article/when-the-sea-saved-humanity-2012-12-07/

Elaborates the theory that when almost all humans died out in the ice ages, a group survived on the southern coast of Africa.

Although scientists lack a precise time line for the origin and near extinction of our species, we can surmise from the fossil record that our forebears arose throughout Africa shortly before 195,000 years ago. Back then the climate was mild and food was plentiful; life was good. But around 195,000 years ago, conditions began to deteriorate. The planet entered a long glacial stage known as Marine Isotope Stage 6 (MIS6) that lasted until roughly 123,000 years ago.

...While the planet was in the grip of this icy regime, the number of people plummeted, and only a subset contributed to the surviving population. Geneticists debate how small this population was, but it could have been as few as several hundred individuals. Estimates of the timing of the bottleneck tend to be at around 150,000 years ago.

Lots more in the article, the evidence is sketchy but it's fun to speculate on it.