This is a common fate in human prehistory.

The history of human populations is not a history of clean lineages marching forward in time, each group maintaining its genetic distinctiveness from generation to generation.

It is a history of constant mixing, migration, replacement, and absorption.

Populations meet and mix.

The people of one region adopt the people of another region into their communities through marriage, through conflict, through migration.

Over time, what was once a distinct genetic cluster becomes a component — sometimes a small and difficult-to-detect component — of later, more diverse populations.