The reLOH event of 22/23, and a step back, likely took place much earlier than 500 AD. There are several interesting links in the New York Times article about Olalde's paper published in 2019 https://www.nytimes.com/2019/03/14/science/iberia-prehistory-dna.html It's an interesting read.
Rollo, the first Duke of Normandy was Scandinavian. Charles III ceded Rollo part of Nuestria, in France, during the 10th Century. The Frankish King entered this treaty in hopes of ending Viking raids along the Seine. The ploy was not effective. The raids continued. There is no specific genetic testing for Normans or Vikings. Both terms are relative. They vary from region to region
Please note, our pedigree of Walter d'Alton and 'Princess' Jane, in the Heralds Office, is based on 'tradition'. Historically, that means there is no documentation. Copies were obtained in 2005. Extensive research has now been accomplished.
The Flight of the Earls was a sad period in Irish history. Many founding families fled Ireland. They offered their military services to other countries. Count Richard d'Alton was titled by Maria Teresa of Austria. https://ukga.org/index.php?pageid=32274 Baron Alexandre d'Alton was titled in 1809 by Napoleon. His father, William d'Alton was a Captain in the Brive Infantry. Do you descend from our Mount Dalton or Windgap Daltons?
Genetically, Clan Dalton was not representative of the area they departed. Nor was Clan Dalton representative of the area they colonized in Ireland, during the 12th Century. Their rare alleles survive ten centuries later. YFULL age estimation is currently confirming our first known ancestor in the twelfth century. All things genetic being fluid, this could change.
Very exciting to corroborate supporting documentation with genetics