The correct answer to this open question is the following.
The discovery of this commodity in southern Sudan sparked the independence movement that eventually led to the division of the country. We are talking about oil.
South Sudan is a complex place. It has many different people from Africa. That diversity has been the cause of some conflicts. South Sudan became independent from Sudan until July 2011, after so much struggle and conflicts. A precious natural resource as oil was the reason for so many conflicts.
One could think that after South Sudan gained independence, things started to go well. But unfortunately for them, That was not the case. In 2013, the country started a civil war.