Once upon a time, in an alternate reality, the South successfully seceded and slavery was still legal in parts of America.

That’s the premise of Confederate — an upcoming HBO series that has faced critical backlash since it was announced Wednesday via press release.

“I suppose it’s an interesting premise, but as is often the case with interesting premises, at what cost?” author Roxane Gayasked in the New York Times. “It has been more than 150 years since the Civil War ended, but it often feels like some people are still living in the antebellum era.”

So is it too soon?

Creators D.B. Weiss and David Benioff -- of Game of Thrones fame -- and executive producers Malcolm and Nichelle Spellman want to explore an alternate history through a counterfactual drama. But historians advise it may be too soon to delve into such precarious and delicate material.

“Counter-factual history is an exercise in creative imagination,” Koehn said in an interview with Boston Public Radio Tuesday. “It’s not an exercise in analytics, it’s not an exercise in the evidence.”

“It’s purely fiction,” Koehn continued. “To think that you’re going to somehow do something to expand the intellectual or historical resources or library of the American people is to indulge in, I think, a slightly egotistical exercise, but largely in wishful thinking.”

Nancy Koehn holds the James E. Robison Chair of Business Administration at Harvard Business School. Her forthcoming book is Forged in Crisis: The Power of Courageous Leadership in Turbulent Times. To hear her entire segment with Boston Public Radio, click on the audio player above.