As for the -nthos, -ssos place names, they seem to be Thracian too.
Now I'm getting closer to home!
From Ivan Duridanov's site, on Thracian
http://members.uk.tripod.de/Groznijat/thrac/index.html
Apsinthos, Apsynthos (Dion., Steph. Byz.) - a frontier river and a
main settlement of the tribe of Apsinthioi (Hdt.) to the north of the
Thracian Chersones (modern Galipoli peninsula); Apsinthis (Apsynthis)
(Strab., Steph. Byz.) - the country of the same tribe. The name is
linked with apsinthion `wormwood', a word thought to be of Pelasgian
origin in the Greek language, or with the Illyrian river name Apsus,
derived from the IE *a^p- respectively *ab- `water, river'. My
opinion is that it is probably connected with the IE *apsa: `aspen',
attested in the Latv. apse, the Old-Pruss. abse, the Lith. apus^e:,
the Pol. osa, osina, Old-HighGerman aspa. Compare with the Old-Pruss.
place name Abs-medie, Ans-wangen, the Lith. Aps^-lavas (a lake), the
river name Aps^-riuotis.
Asamus (Plin.) - the modern river of Os&m. The name was interpreted
long time ago as `stony river' from the IE *ak'amo- `stony' in the
Old-Ind. asman- `stone; sky', the Avest. asman `the same', the
Pelasg. asaminthos '(stone) bath', the Lith. akmuo, -eñs `stone'.
This interpretation fits perfectly to the character of Os&m, with
stony bed in its upper and partially in its middle course. Compare
with Assamum (a town in Dalmatia), which was renamed in the middle
ages in Larida from the Latin lapis, -idis `stone'.
Périnthos (Hdt., Ptol.), Perinthus (Liv., Plin.) - town on Propontida
in Thracia, today Heraclea, the Turkish Eregli. The name is probably
an extension with the IE suffix -nt-, resp. -ent- of the stem *per(u)-
`a rock', in the Hett. peruna- `a rock' and the Old-Ind. párvata- `a
mountain' - the IE *per-to-. A genetic link with the name of the
Bulgarian mountain of Pirin (Perin) is doubtful.
Ze:'rynthos (Steph. Byz.), Ze:'rybthion (Suid.), Ze:'rinthon (Schol.
ad Lykophr.), Ze:'rynthon (Etym. M.), Zerynthium (Liv.) - a cave and
a town on the island of Samothraci and in Thracia. The name can be
compared to the Lith. river name z^veriñc^ius from the basis z^verint-
, a derivative from the Lith. verìs `a beast', related to the Old-
Bulg. zver& `a beast', the Greek the:r - from the IE *g'WHe:r-.
Harpessós (App.) - river in Thracia, a tributary of Hebros. It can be
reconstructed as the Thracian *Varpassas (resp. *Varpatyas), which
was interpreted in Greek as *Arpesos and received the initial H-
after words such as the Greek hárpax `predatory', hárpe `a falcon'.
Related to the Thracian name are the Latv. va^rpats `whirlpool', the
Lith. varpy^ti (-paû, -piaû) `to dig' as well as a number of Baltic
place names: the Old-Pruss. Warpen, Warpunen, the Lith. river names
Var^pe, Varputy^s, Várpapievis, etc.
Kurpisos (in an inscription) - village in Thracia, probably in the
Chirpan district. The name obviously contains the suffix -is- and
kurp and is related to the Lith. place name Kurpykámas, Kurpu-laukis,
the Latv. Kazû-kurpe, Kurpes-grâvis, Kurp-kalns, etc., explained from
the Lith. kur^pti (-iù) `to dig', similar to the Russ. korpat' `dig
around', the Ukr. korpati `to dig' from the Proto-Slavic *k&rpati.
From the same stem are also the Bulg. village name K&rpec and the
Croat. Krpec.
Panisas (Plin., variants: Pannisis, Panisa, Panissa) - coastal river
in the region Tjunias in Turkish Thracia. The name is a derivative
with a suffix -is- of the Thracian *pan(i) `swamp, bog' (see for
detail under Panax).
Pannysis (Plin., Variants: Pannisis, Panysis, Panysus), Pans(s)os
(Ptol.) - the modern Kamchija river; Pannisus (Tan. Peut.) - station
on the Kamchija river. The name is identical with the previous one.
Zilmissus (in a literary source) - hill in Thracia. The name is
derivative with a suffix from the basis zilma- from the IE *g'hl.mo-
or -d, related to the Lith. river name z^ilmà, z^ilmas (a lake), the
Latv. zelme `green grass or wheat'.
BTW, please note
Germanía (Prok.) - town in the region of Pautalia (Kjustendil),
today - Sapareva banja. The town was situated along the river of
Dzherman, previously known as Germanica (1378 AD), German (1479),
from the antique German-. It is explained from the IE *ghermo- `warm'
in the Old-Ind. gharmá `heat', the Armen. jerm `warm', the Greek
themós `the same'. The Thracian village obviously got its name from
the river name of *Germana (resp. -as). Similar name is attested in
the Baltics: Germona (in a Russian source from 1559 AD).
Did the Odin people stay here before moving on to Saxland, named
Germani?
Torsten