From the Wikipedia page 
Ruvuma Region is one of Tanzania's 31 administrative regions. The regional capital is the municipality of Songea.
The region is named after the Ruvuma River, which forms most of its southern boundary with Portuguese-speaking Mozambique (where it is known as «Rovuma»). The region is also bordered to the north by the Morogoro Region, to the northeast by the Lindi Region, to the east by the Mtwara Region, and to the northwest by the Njombe Region.