The prevailing view is that this admixture occurred primarily in western Asia — in the Levant, or possibly in southeastern Europe — during the earliest phase of modern human expansion out of Africa, when populations of Homo sapiens first encountered Neanderthal populations that had inhabited those regions for hundreds of thousands of years.

The admixture was not, as far as the evidence shows, a single event.

It appears to have occurred over a period of time, in multiple episodes, as modern and Neanderthal groups came into contact repeatedly.

But the main genetic legacy of these encounters was established during that initial encounter period, and the proportion of Neanderthal ancestry — roughly one to four percent in all non-African modern humans today — was established at that time.

The Zlatý kůň analysis helped constrain when this initial encounter happened, because the unusually long Neanderthal segments in her genome indicate that her ancestry traces relatively directly to those first encounters.