'northern region' is correct and usable in written English.
For example, you can use it in a sentence like, "The northern region of the country is experiencing a drought."
EIM Annual emission of carbon to the atmosphere in the Northern Region from products made from wood harvested outside of the Northern Region and imported into The Northern Region.
The Northern region of Ghana consists of 18 administrative districts with Tamale as its regional capital.
The northern region remains under Houthi control.
This northern region has been hit particularly hard by depopulation.
Asturias, a much smaller northern region, was also voting.
Arusha, formerly Northern Region, administrative region, northern Tanzania, East Africa.
Tamale is the capital of the Northern Region of Ghana.
Zande and Mangbetu art are included in the northern region.
Mali's northern region was engulfed by fighting during the 2012 conflict.
But the party's poll ratings in the northern region continue to rise.
A typical pasta dish from the northern region of Emilia-Romagna.
