The land border consists of two parts: the northern part stretches across Carpathian Mountains region roughly west-east from the Hungary-Romania-Ukraine tripoint to the northern Moldova-Romania-Ukraine tripoint. It starts along the Tisza River (through Maramureș) and runs across the historical region of Bukovina in the Eastern Carpathians. The southern part stretches between Budjak and Dobrudja regions roughly west-east from the southern Moldova-Romania-Ukraine tripoint to the maritime Romania-Ukraine boundary. It runs along the Danube River, its Chilia branch (most northern branch) of its delta to the Black Sea. Until Soviet occupation of Bessarabia and Northern Bukovina, Dniester (Nistru) river used to serve as international border between Ukraine (later the Ukrainian SSR) and Romania.