From the Wikipedia page [1]

Simanjiro District is one of the six districts of the Manyara Region of Tanzania. It is bordered to the north by Arusha Region, to the north east by Kilimanjaro Region, to the south east by Tanga Region, to the south by Kiteto District, to the south west by Dodoma Region and to the west by Babati Rural District. The district headquarters are located in Orkesumet.