Some maps are in order; this is just an unfamiliar part of the world for most folks.
The Scramble for Africa. Look how fast Europeans conquered the continent! By 1913, the independent African countries were Liberia (but not really AFRICAN, it was more of a weird settler state kinda thing, which is why I don't count it), parts of the Senussi tribes in Libya (though they would be conquered in the 1920s), and of course...Ethiopia.
Ethiopia around 1887. These are the major "princedoms" of Christian Ethiopia, note A. the location of Dogali, initial Ethiopian victory over Italy, and B. the locations of Tigray and Showa - the lands of Ras Mengesha and Negus Menelik, the two rivals for the throne of Ethiopia in 1889.
Ethiopia united under Menelik 1889-1895; see the new Italian colony of Eritrea, the new Ethiopian capital of Addis Ababa, and Menelik's expansions to the south and east to consolidate his rule.
Ethiopia after Menelik's victory at Adwa, 1896. Note the location of Adwa/Adua.
Menelik's march to Adwa.
The Battle of Adwa - maps from Raymond Jonas's book, cited below
SOURCES
Adejumobi, Saheed A. The History of Ethiopia. London: Greenwood Press, 2011.
Dunn, John. "For God, Emperor and Country! The Evolution of Ethiopia's Nineteenth-Century Army." War in History 1994, Vol. 1 (3) p. 278-299.
Jonas, Raymond. The Battle of Adwa: African Victory in the Age of Empire. Cambridge: Belknap Press of Harvard University Press, 2011.
Marcus, Harold G. The Life and Times of Menelik II: Ethiopia, 1844–1913. Lawrenceville, N.J.: Red Sea Press, 1995.
McLachlan, Sean. Armies of the Adowa Campaign 1896: The Italian Disaster in Ethiopia. Oxford: Osprey, 2011.
Milikias, Paulos & Getachew Metaferig. The Battle of Adwa: Reflections on Ethiopia's Historic Victory against European Colonialism. New York: Algora, 2005.
Pakenham, Thomas. The Scramble for Africa: The White Man's Conquest of the Dark Continent from 1876 to 1912. London: Random House, 1991.
Vandervort, Bruce. Wars Of Imperial Conquest In Africa, 1830-1914. London: UCL Press, 1998.