Maritsa
It has its origin in the Rila Mountains in Western Bulgaria , flowing southeast between the Balkan and Rhodope Mountains , past Plovdiv and Parvomay ( where the Mechka and the Kayaliyka join it ) to Edirne , Turkey . 
<triplet> Rila Mountains <subj> Bulgaria <obj> country <triplet> Balkan <subj> Bulgaria <obj> country <triplet> Edirne <subj> Turkey <obj> country