From the Wikipedia page 
Uyui District is one of the seven districts of the Tabora Region of Tanzania. It is bordered to the north by Nzega District and Igunga District as well as by the Shinyanga Region, to the south by Sikonge District, to the west by Urambo District and Kaliua District, and to the east by the Singida Region. Tabora Urban District is an enclave within the Uyui District. Its administrative seat is the city of Tabora.