Gunma is the northwestern-most prefecture of the Kanto, and is mostly mountainous in the north, with more of the population concentrated in the southern half facing Saitama Prefecture.
On January 23, 2006, the municipalities of Gunma, Kurabuchi and Misato from GunmaDistrict and the town of Shin from Tano District merged into the expanded city of Takasaki.
NittaDistrict and Yamada District were dissolved as a result of this merger.