The above map shows the original area where Celts settled in Central Europe. From this region, the Celts expanded. One distinguishes thereby between prehistoric expansions before 500 B. and later historical migrations.
Celtic Expansion across Europe; these people were not just found in Ireland where the majority of their populations are. They were even found in the Roman Empire and they even Looted Delphi in 279 B. They were forced west due to Germanic Tribes.