Southern Serbia or sometimes referred to as Southeastern Serbia, Southern Pomoravlje, South of Central Serbia, historically known as New Serbia or New Territories, is a macroregion in Republic of Serbia which most often refers to the territories of Nišava, Toplica, Jablanica, Pčinja and Pirot Districts. This region occupies about 14,000 square kilometers and is home to about 1,000,000 people. More than a quarter of the population in the region lives in the city of Niš.

The Nišava District is one of nine administrative districts of Southern and Eastern Serbia. It expands to the south-eastern parts of Serbia. According to the 2022 census results, it has a population of 343,950 inhabitants. The administrative center of the district is the city of Niš. After South Bačka, it is second largest District in Serbia.