Simiyu Region is one of Tanzania's 31 administrative regions. The region covers a land area of 25,212 km2 (9,734 sq mi). The region is comparable in size to the combined land area of the nation state of North Macedonia. The region is bordered to the north by the Mara Region, to the south by the Shinyanga Region and Singida Region. Mwanza Region borders the region to the west through Lake Victoria, and Arusha Region to the east. The region is home to the Serengeti National Park, a UNESCO World Heritage Site, shared with Mara Region. The regional capital is the town of Bariadi. According to the 2022 national census, the region had a population of 2,140,497.

The Sukuma are a Bantu ethnic group from the southeastern African Great Lakes region. They are the largest ethnic group in Tanzania, with an estimated 10 million members or 16 percent of the country's total population. Sukuma means "north" and refers to "people of the north." The Sukuma refer to themselves as Basukuma (plural) and Nsukuma (singular).