Northerners cannot continue with their decision of not supplying foodstuffs to the Southern Nigeria because of two major reasons.
The first reason is that, the population in the south that patronizes the northern traders cannot be found in any Central or West African countries, therefore the money they make in Southern Nigeria may not be made in Chad, Niger and Cameroon put together, only Lagos, Rivers, Anambra, Abia and Oyo population is up to the population of the aforementioned countries.
They realised that they are losing a lot by not supplying foodstuffs to the South, where they make a lot of money, and they quickly reversed their decision.
Secondly, due to the nature of their goods, which are perishable, coupled with low patronage in the neighboring countries, where they had decided to go and sell their farm produce, most of the goods started spoiling, making them to lose heavily.
The two reasons will make it hard for northern traders to sustain their decision of not supplying foodstuffs to the South.