The greater part of this Neanderthal DNA showed up in a 7,000-year time frame around quite a while back, after present day people emerged from Africa into Europe, and before Neanderthals became wiped out around a long time back. During this time there probably been numerous pairings among Neanderthals and people.
To some degree half of the entire Neanderthal genome can be sorted out from sections tracked down in the genomes of various contemporary people. We have our Neanderthal progenitors to thank for qualities including red hair, joint pain and protection from certain illnesses.