Shinyanga Region is one of Tanzania's 31 administrative regions. The region covers a land area of 18,555 km2 (7,164 sq mi). The region is comparable in size to the combined land area of the nation state of Fiji. The region is bordered to the north by the Mwanza, Mara, and Kagera Regions and to the south by the Tabora Region. In addition, the Kigoma Region borders the region to the west, and the Simiyu Region and a sliver of Singida Region to the east. The regional capital is the municipality of Shinyanga. According to the 2022 national census, the region had a population of 2,241,299.

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.