What is behind rising tribal tensions in Sudan?

Violence in Blue Nile state triggers protests in several cities.

Over the past week, Sudan has seen some of its worst tribal violence in years.

At least 79 people have been killed in Blue Nile state.

Fighting between the Berti and Hausa tribes is being blamed on issues including long-running tribal disputes, land access, and tensions with leaders in the capital, Khartoum.

It has triggered protests led by Hausa members in neighbouring states...