Rzucewo culture
Tracing formation of the Balts to Rzucewo culture could explain differences between Western and Eastern Balts and their languages ( and possibly a stage of West Baltic–Pre-Slavic unity; see Balto-Slavic languages ) , though linguistic conclusions based on this methodology are controversial and tentative at best , "ad hoc" at worst . 
<triplet> Western <subj> Balto-Slavic languages <obj> part of <triplet> Balto-Slavic languages <subj> Western <obj> has part