Short answers, pulled from the story.
Italian East Africa was proclaimed by Benito Mussolini on the 1st of June 1936 and collapsed in November 1941 following the Battle of Gondar. It existed for approximately five years as a colonial administrative entity of the Kingdom of Italy.
Italian East Africa combined Italian Eritrea and Italian Somaliland, both Italian possessions since the 1880s, with the newly conquered Empire of Ethiopia. The territory was divided into six governorates: Eritrea, Somalia, Harar, Galla-Sidamo, Amhara, and Scioa.
Yekatit 12 refers to the mass killing that followed an assassination attempt against Viceroy Rodolfo Graziani on the 19th of February 1937. Over three days, Italian forces and Blackshirt militias killed thousands of Ethiopian civilians in Addis Ababa; estimates of the death toll range from 1,400 to 30,000. Graziani was subsequently removed and became known as "the Butcher of Ethiopia."
A colonial racial directive issued on the 5th of August 1936 instructed Viceroy Graziani to make the separation of white and black races the guiding principle of policy. The second colonial racial law of June 1939, formally titled "Punishment Measures for the Protection of the Racial Prestige of the Indigenous Peoples of Italian East Africa," institutionalized segregated housing, schools, hospitals, transport, and public spaces, and prohibited interracial marriage.
By the end of 1939, approximately 165,267 Italian civilians were recorded in Italian East Africa, rising to around 170,000 by March 1940. This compares to only about 6,000 Italians present in the region before the invasion of Ethiopia in 1935.
The Treaty of Paris of February 1947 required Italy to renounce sovereignty over its African colonies and pay Ethiopia twenty-five million US dollars in war reparations. Eritrea was federated with Ethiopia in 1952. Former Italian Somaliland became independent on the 1st of July 1960 and united with British Somaliland to form the Somali Republic.