The area south of Mt. Bruce is in the Wellington Region and is always known as Wairarapa or in some circles, the 'Wairarapz'. It contains Masterton District, Carterton District, and South Wairarapa District. It is separated from Upper Hutt and Lower Hutt cities by the Tararua Ranges in the north and the Rimutaka Ranges (also known as the Rimutakz) in the south.
The district's northern borders are vague, and there is some overlap with southern Hawke's Bay. Part of the reason is that the area was settled from both the north and the west and has been the subject of several reorganisations of local government.
The area to the north of Mt. Bruce, extending through Pahiatua and Woodville to about Dannevirke, is called the Tararua (with a district council of the same name) and is in the Manawatu-Wanganui region, because it is in the catchment of the headwaters of the Manawatu River. The river runs westward between the ends of two mountain ranges (Tararua, already mentioned, to the south and the Ruahine Ranges to the north) via the Manawatu Gorge to pass Palmerston North and reach the west coast of the North Island.
The east coast contains settlements such as Tinui, Castlepoint, and Riversdale, while the main southern rivers drain through or past Lake Wairarapa to discharge into Palliser Bay east of Cook Strait.
Rangitane and Ngati Kahungunu were the Maori tribes (Iwi) in the area when European explorers arrived in the 1770s.
European settlement began in the early 1840s, initially on large grazing runs leased from Maori, but with closer settlement from the 1850s.
On January 23, 1855 the region was hit by the strongest Earthquake ever recorded in New Zealand, which reached Magnitude 8.1 on the Richter Scale. There were five deaths.
Many residents, especially in the western towns such as Featherston and Greytown, commute to work in Wellington, either by train (which has used the Rimutaka Tunnel since 1955) or over the Rimutaka Ranges by road.