Rollo was a duke of France as far as I can read on the internet
"was a Viking who became the first ruler of Normandy, a region of France. He is sometimes called the 1st Duke of Normandy. His Scandinavian name Rolf was extended to Gaange Rolf because he as an adult became too heavy for a horse to carry, therefore he had to walk ("gaa" in older Dano-Norwegian). Rollo emerged as the outstanding personality among the Norsemen who had secured a permanent foothold on Frankish soil in the valley of the lower Seine. Charles the Simple, the king of West Francia, ceded them lands between the mouth of the Seine and what is now the city of Rouen in exchange for Rollo agreeing to end his brigandage, and provide the Franks with protection against future Viking raids."
So the Gauls,Franks, and Vikings was actually mixed? that is new to me.