Historian Catherine Fletcher was researching the Roman court for a previous book when she came upon the story of Alessandro de’ Medici, whose rule of Florence had been brief and violent — thrust into power at 20, he was assassinated at 26. Even against the dramatic backdrop of 16th-century Florence, Alessandro’s story was unique. An illegitimate son born to a household slave, rumored to be “an African or mixed race woman,’’ Fletcher said, Alessandro “might be said to be the first person of color to rule a modern Western state.’’

“The Renaissance is a period which we often associate with quite traditional history: death, white men, and so forth,’’ Fletcher said. “As soon as you go looking for evidence of black people in these historical sources, you suddenly find loads: There are black pages at court; there are black musicians. In some ways, it’s not only about Alessandro, but it’s that this whole society was perhaps more diverse than we think.’’

In “The Black Prince of Florence: The Spectacular Life and Treacherous World of Alessandro de’ Medici,’’ Fletcher writes not only of the prince’s life but of how history has regarded him. In the 19th-century era of scientific racism, she said, Alessandro was disparaged as an example of black inferiority, while early 20th-century historians of the African diaspora hailed his significance.

Reclaiming Alessandro and placing him in his diverse world is important, Fletcher said, “because you will still today get people making historical movies set in the Renaissance or medieval period who say, ‘Well we can’t include people of color in the cast, because that’s not historically accurate or appropriate.’ Perhaps the reason for doing this type of research and writing about it is to say, ‘Well actually, that’s not true.’ ’’

Fletcher will read at 3 p.m. Sunday at Concord Bookshop and 7 p.m. Monday at Newtonville Books.

Kate Tuttle, a writer and editor, can be reached at kate.tuttle@gmail.com