The great capital of Addis Ababa is patrolled by soldiers who speak provincial Tigrinya and not the local tongue and Ethiopian national language, Amharic. That can lead to confusion and conflict. The Tigreans rebelled against the imperialism of the Amhara, whether under theocratic emperor or Marxist junta. Now the Amhara not unreasonably fear the shoe on the other foot.
Ethiopian rulers had clout on the Red Sea coast until the 16th century, when the Turks invaded. At the end of the 19th century, Italy beat out Egypt and Ethiopia to set up the modern colony of Eritrea. Eritrean identity is an Italian invention. An Italian attempt to conquer Ethiopia was crushed in 1895 at Adowa (now a rebel-held town in Tigre) and Ethiopia won recognition as a modern state.
In 1935, Italy did conquer Ethiopia and unite it with Eritrea. Britain ousted Italy in 1941, freeing Ethiopia and separating it from Eritrea, which became a British protectorate. British withdrawal in 1952 left Eritrea, by United Nations edict, as an autonomous province of federal Ethiopia. Ten years later, Emperor Haile Selassie incorporated Eritrea wholly into his realm, provoking rebellion. The Marxist officers who overthrew the emperor should have come to terms with Eritrean autonomism, but instead became more imperialist.