Short answers, pulled from the story.
Yekuno Amlak founded the Ethiopian Empire in 1270 after defeating the Zagwe king at the Battle of Ansata. He claimed descent from King Solomon and the Queen of Sheba through the Kebra Nagast text.
Emperor Haile Selassie abolished slavery throughout the empire on the 27th of August 1942. The law imposed severe penalties including death for slave trading.
Italian soldiers under Marshal Emilio De Bono began the Second Italo-Ethiopian War in 1935 using sulfur mustard chemical warfare. Addis Ababa was occupied on the 5th of May 1936 before an Italian victory was declared on the 9th of May 1936.
According to Bahrey there were ten social groups in feudal Ethiopia including monks debtera lay officials men at arms lords hereditary landowners farm laborers traders artisans wandering singers and soldiers called chewa.
The monarchy was formally abolished in March 1975 after the Derg deposed Emperor Haile Selassie on the 12th of September 1974. Marxism-Leninism was proclaimed the new ideology of the state.