source: It has long been the economic centre of norther Nigeria along with the center for production and export of groundnuts.
target: The production and export of groundnuts has been a main source of income in Northern Nigeria.
references: The production and export of groundnuts has been a main source of income in Northern Nigeria. It has been the economic centre of Nigeria and a centre for production and export of groundnuts. It has long been the of money and goods middle of the north Nigeria, and a middle for the producing and sent to another country of groundnuts. It has been the economic centre of northern Nigeria for a long time; it produces groundnuts and ships them to other countries. the economic centre of northern nigeria is the area for the production and export of groundnuts. Its the economic centre of northern Nigeria which also a centre for the production and export of groundnuts. It has long been the economic centre of northern Nigeria, and a centre for the production and export of groundnuts.