I learned about them YEARS ago when studying for the Ministry.
Apparently they were from the North and nomadic, and as they chose Judaism in preference to Islam so gaining “Children of the Book” status and thus avoiding the “islamic convert or die” dictate so retaining much of their traditions, identities, and culture.
By the 8th century and at the same time as they met islam on the ground it be blocking them from Christianity. This as a result of the terrorism and conquest by islamic forces as they raped and pillaged their way across Europe.
So the answer is that they probably were eventually assimilated into islam, or Christianity when they had the chance.
As I recall the only basis for any claim that they were in any real way associated with Judaism was as a result of their own choice as a means of avoiding “conversion by the Sword” yet still being able to pretty much carry on their own lifestyle unhindered by the demands and oppression of islam and that is all.