That culture had its roots in the events much earlier, when 125 thousands years ago the temperatures were about 4 degrees warmer than today, and the droughts in central Africa pushed humans in search of the new lands.
In the following 20 thousands years humans colonized much of the Eurasia, they were competing with other hominids and great mammals, but they became successful never-the-less. Eventually they developed a great oral culture, arts, poetry, they lived of the land and they mostly spoke the similar languages. They colonized Europe all the way from Ural Mountains to Scandinavia and British Isles.
When 105 thousand years ago the climate started to cool down to about 3 degrees less than today, and the glaciers returned to the Northern Europe, the human population was already established and thriving.
At the time of the story, 71 thousand years ago, there were well over 150 thousand humans spread across Africa, Europe and Southern Asia.
That is when the disaster came and wiped out humanity.
The explosion of Indonesian volcano Toba was not unusual in the history of the Earth, in fact gigantic caldera explosions happens at least every 100 thousand years.
Yet, the 750 cubic miles of ash thrown into the atmosphere by Toba was a thousand times stronger any volcanic explosion in the modern times, including the 1982 eruption of Mt. St. Helen. In comparison tiny explosion of Philippine's Krakatoa in 536 AD darkened the sun for eighteen months, and the explosion of Mount Tambor in 1816 caused the "Year without a summer" resulting the widespread famine and related diseases which wiped out 200,000 people, or one-third of Europe.
The explosion of Toba in Sumatra was absolutely devastating, the ashes suspended in the stratosphere caused a six-year volcanic winter, with the crop failures and caused the already cold temperatures to plummet another several degrees. The whole world fell in one of the deepest ice ages. About 90 percent of the humanity starved to death, the remaining 15 thousand or so, were too small of the gene pool to rebound and for all practical purposes disappeared for the next 60 thousand years.
