World of Africa: Why is Ethiopia at war with itself?

The war between the Ethiopian government and its allies against Tigray, one of its northern states, has led to a humanitarian crisis. Tigray was an environmental success story, but the war is undoing decades of regreening. Prime minister Abiy Ahmed and the Tigray people’s liberation front or the TPLF have been at loggerheads since 2020. Now after over a year of the war, leaving millions displaced and thousands dead, both parties have asserted their desire for peaceful negotiations to find an end to the conflict. But how did the civil war begin?