Slavic peoples in what is now east Germany

From: MCLSSAA2@...
Message: 7502
Date: 2001-06-08

--- In cybalist@..., tgpedersen@... wrote:
> Another strange idea. Odin stopped in Germany first and built a
> kingdom there. Let's assume he stopped in Thuringia (Saxo: Tanna,
who
> was defeated in Byzantium, travels to the Wilcze and defeats them.
> The Wend tribe of Wilcze lived close to the Saale River. That's very
> close to Thuringia). ...

How much is known about these various Slavonic peoples who lived in
what is now eastern Germany, and when they lost their identity and
language? I have heard of: Obotrites (Mecklenburg); Havolane (around
the river Havol = Havel in the region of Berlin; Sprevjane (around the
river Sprevja = Spree); Polabe (in the southewest); Sorbs alias Wends
(in the south; their language persists to this day in Lusatia =
Lausitz); Wiltzes (in Brandenburg) and others whse names I forget now.

What do Slavic placenames "X-owitse" or "X-onitse" mean? Does it mean
"X-stream" or "X-place" or what?