From the Wikipedia page 
Kilwa one of the 6 districts of the Lindi Region of Tanzania. It is bordered to the North by the Pwani Region, to the East by the Indian Ocean, to the South by the Lindi Rural District and to the West by the Liwale District. The district includes the island of Kilwa Kisiwani in the Indian Ocean.
Recent (2003 through to at least 2007) developments in the area include the development of a significant natural gas field underlying the Songo Songo Island group in the Indian Ocean, and continuing efforts to locate hydrocarbon reserves (oil and/or gas) along structural trends sround the Songo Songo group at least as far north as the island of Nyuni. These researches have not been completed. These developments have already made the district economically important, and as industries are developed along the pipeline route, this level of economic importance is expected to be increased, even if the other hydrocarbon searches are unsuccessful.