Azerbaijan–Russia border
Prior to 1991 it formed the border between the Russian Soviet Federative Socialist Republic ( including Dagestan ASSR ) and the Azerbaijan SSR within the Soviet Union . 
<triplet> Russian Soviet Federative Socialist Republic <subj> Soviet Union <obj> country <triplet> Dagestan ASSR <subj> Russian Soviet Federative Socialist Republic <obj> located in the administrative territorial entity <subj> Soviet Union <obj> country <triplet> Azerbaijan SSR <subj> Soviet Union <obj> country <triplet> Soviet Union <subj> Russian Soviet Federative Socialist Republic <obj> contains administrative territorial entity <subj> Azerbaijan SSR <obj> contains administrative territorial entity