[muawiyah]

That's the old now discredited theory. They are all readily differentiated by their DNA ~ language and cultural similarities simply didn't do the job.

The Germans, in any case, were tributary to the Celtic speakers along the lower Danube.

Gaelic was brought into the British Isles as recently as 700 BC by Celts who'd former lived in the Black Sea region (see Danube). They took over Spain. Over the next few hundred years they cleverly enslaved their neighbors (today's Basques) and took them to Hibernia. Today's Irish and the Basques are remarkably identical in mtDNA and other markers, although their languages are vastly different.

[MarkBsnr]

Mitochondrial DNA is a powerful tool, admittedly. Yet, we have the Celts moving west, not east. I don’t see the support of the statement that the Germans were influenced genetically by the Celts moving back east.