[QUOTE=Laevex]

Thrace = Thraikia
Thracians = Thraikes (plural)
Thracian (n.) = Thraix (singular)
Thracian (adj.) = Thrakios (singular) and Thraikioi (plural)

Scythia = Skythia
Scythians = Skythai/Skythes?
Scythian (n.) = Skythes (singular)
Scythian (adj.) = Skythios/Skythikos (singular) Skythioi/Skythikoi (plural)

Seleucid Empire = Arche Seleukeia
Seleucids = Seleukeioi Seleukidai=From Seleukos
http://en.wiktionary.org/wiki/%CE%A3...B4%CE%B7%CF%82
Seleukideis=from Seleukeia
http://en.wiktionary.org/wiki/%CE%A3...B5%CF%8D%CF%82
Seleucid (n.) = Seleukid as above, Seleukides(singular)=From Seleukos and Seleukeus=From Seleukeia
Seleucid (adj.) = Seleukeios (singular)/ Seleukeioi (plural)

QUOTE]

Note that one of two of the above are highly contested, still they are better than nothing.

Hope I helped!
Best of luck with the AAR.