It is telling that no one has ever answered Wojciech Ketrzynski when he raised questions about the ethnicity of the Suevi.

The mainline teaching is:

Suevi occupied most of Germania

After Suevi disappeared, they were replaced by Slavs who came somewhere from the East

Slavs have nothing to do with the Suevi because the latter were “Germanic”.

Several questions come to mind:

I. How is it possible that this giant tribal union devolved into nothing?

The Suevi of later years are:

the smallest contingent crossing the Rhine in 405/406;

the Suevi of Swabia;

the Suevi of Vannius;

The first group was small. As to the second group, German writers have went out of their way to draw an equal sign between the Schwaben and Alemanni. And yet the entry of the Alemanni suggests that the later Schwabia has as much to do with the Suevic Suavia as 19th century Prussia with 13th century one. The Suevi may well have left years before the Alemanni got there. The same claim is made about Bohemia with the Czechs taking the name of the Bohemians who had been driven out years before (or were the Czechs just coming back?).

II. How is it possible that when the “fog of war” clears, the Suevic area is entirely occupied by Slavs?

If the Suevi left the area, they did not leave it empty. And if they did then plenty of other invaders who would have kept portions of the country. But there are only Slavs.

What happened to Ockham’s Razor? Did historians leave it at home?

VIII. If the Slavs borrowed terms from “Iranian” languages, why couldn’t they have borrowed them from the Jazyges?

Because the Slavs did no live next to the Jazyges. The Suevi did. If they spoke an Iranian language, then the Danube Suevi-Jazyges connection could have provided all the materials needed.