Recommended Books
General History
Layers of time: a history of Ethiopia: https://books.google.com.au/books/about/Layers_of_Time.html?id=gzwoedwOkQMC&redir_esc=y
Ancient History
Aksum: an African civilisation of late antiquity:
https://archive.org/details/aksumafricancivi0000munr/page/28/mode/2up
Ancient and Medieval Ethiopian History to 1270 by Sergew Hable Selassie:
https://archive.org/details/ancient-and-medieval-ethiopian-history-to-1270
Medieval
A Companion to Medieval Ethiopia and Eritrea:
https://www.amazon.com.au/Companion-Medieval-Ethiopia-Eritrea/dp/9004419438
Church and State in Ethiopia, 1270-1527:
Peripheral Societies
The Ethiopian Borderlands:
https://books.google.com.au/books/about/The_Ethiopian_Borderlands.html?id=zpYBD3bzW1wC&redir_esc=y
Medri Bahri
Traditions de Tsazzega et Hazzega:
https://archive.org/details/traditionsdetsaz03kolm/page/30/mode/2up
Bilen
The Blin of Bogos, by Michael Ghabe: