origin of the Germanic tribes, in Scandinavia peninsula or German co

Many thanks for your answers to my question. But I should like
to know more about the origin of the origin of the Germanic tribes.

There is two possibilies:
1) all the Germanic tribes (included Saxons, Franks) had a
Swedish or Norwegian origin; when did the Germanic speaking
arrive there?
2) once the Germanic tribes only lived on the German (maybe Dutch and
Danish countries) continent. I cannot believe that the Germanics
origally lived simoultanously in Sweden and in Germany;

I also was strucken by the presence of Germanic tribes (Bronze Age)
only on the Swedish coast. Who did live in the inlands of Sweden?
Were these interior areas unpopulated? And in the north? I suppose
th Sami arrived there at the begin of the era.