What part of Europe did the Keltic Nordic types probably originate from?

I'm unclear as to whether it would be north of the alps, south of the Pyrenees in northern Spain, or southern France. Based on what I've read they came from somewhere in southern or southwestern Europe. However, if that is accurate, how did they become so distinct from the dinarics and alpinids of the same areas? Also, are they a western continuation of the Hallstatt type or a nordic type that evolved seperately?

Also, does anyone have a basic chronology of when the various subraces may have entered history? For example, Cro-Magnons-40,000 years ago, Brunns-20,000 years ago?, Nordics-5000 BC, etc.