In this elegant account, Aida Edemariam has sketched her grandmother’s life in an Ethiopia that shifted, within 50 years, from feudal monarchy to Marxist dictatorship. We first meet Yètèmegnu in the years before the Italian invasion in 1935, as a child of nine betrothed to a cleric more than two decades her senior. It is with a deft, subtle touch that Edemariam portrays both the contemporary celebration of the event and the deeper tragedy of it.

Born into a landowning family in the Gondar region in the north of the then Abyssinian empire, Yètèmegnu boasts distant royal connections. Within her small, pastoral world she is treated as a noble; her larder brims with crops from her husband’s peasant-tilled fields.

It is a world marked by fasting days and high holidays, of sowing and harvesting, of givers and takers – of beauty and suffering. The peasants are forced to hand over up to 75% of their harvest in various taxes, rents and tithes. Edemariam’s gaze travels from the “silver spears” of eucalyptus leaves to “wobble-humped zebus” and goats “plotting delinquency”. The craggy highlands appear as real as any human character; even Ethiopia’s ubiquitous mules are described with real sympathy.

Living the cloistered life of a cleric’s wife, Yètèmegnu is forbidden from playing with other children or, after a few short lessons, learning to read. This claustrophobic world is soon punctured by the Italian invasion of Abyssinia and the exile of Emperor Haile Selassie to Britain. Edemariam, a Guardian journalist, elucidates how the invasion was resisted by some and welcomed by others. Massive investment in the country’s infrastructure by Mussolini’s fascists and their promotion of men ignored by the imperial government meant that the eventual return of Selassie was met with local ambivalence.

After his restoration in 1941, Yètèmegnu falls back into an enervating cycle of childbirth and illness, the narrative slackening as many years pass with little change. Yètèmegnu’s husband, Tsèga, is the central force in her life but he is shadowy, at times brutal, at other times tender, a talented but low-status man trying to climb the ecclesiastical pole. Tsèga’s success at accruing power and privilege is followed by his downfall and he is arrested on false charges, his confinement freeing Yètèmegnu from her own, and allowing her to travel independently for the first time, in a bid to rescue her husband. We enter an ancient-seeming world of royal courts, courtiers, and the mania of an absolute monarchy that holds everything – from legal appeals to school places to office jobs – within its palm.

With a housewife’s view of history, Yètèmegnu witnesses first-hand the changes – in the food market, the rental market, in education, and in attitudes – that herald the end of Selassie’s rule in 1974. Her own children, educated in boarding schools in which Selassie took a keen interest and pride, are part of the changing guard and leave the country either physically or spiritually. The rise of the Derg (the Marxist-Leninist ruling committee, which engineered the coup against Selassie) and the purges known as the Red Terror from 1976 to 1978 are other catastrophes she must withstand. The growing social mobility from which her husband benefited accelerates to the degree that all of her traditional privileges are torn away and she is forced to live on a small stipend from the Marxist regime.

This is a loving portrait of a grandmother, undiminished by the distances between the author and her subject. Edemariam takes the facts of Yètèmegnu’s life – her illiteracy, her isolation, her submission to her husband and to Selassie – and goes beyond them.

Born sometime in the 1920s, Yètèmegnu has lived her life with forbearance but also with courage, creativity and love; she nourishes many people with her own hands, including the infant of a destitute family left with her during the famine of 1984. The biography is interspersed with prayers to the Virgin Mary and it is clear that in Edemariam’s eyes her grandmother is a kind of mother goddess, giving life to her garden, her animals, her children, her neighbours.

It was Zora Neale Hurston who stated in her 1937 novel Their Eyes Were Watching God that the black woman “is the mule of the world”. But while that phrase occurred to me many times while reading The Wife’s Tale, it is only half the story. Yètèmegnu’s life was one of religious passion and service, and when she was an elderly woman and Haile Selassie’s daughter, Princess Tenangeworq, bowed low to her out of respect for her prophetic abilities, it appears, in the text, as both a historically interesting moment and a testament to Yètèmegnu’s unbroken strength.

• The Wife’s Tale: A Personal History is published by 4th Estate. To order a copy for £14.44 (RRP £16.99) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.