Dan Jones is the author of “The Plantagenets: The Warrior Kings And Queens Who Made England” (Viking), to be published on April 22.

Is it possible for a historian to dig “Game of Thrones”? Short answer: yes. The new season of the HBO smash premieres tonight – and while it is the sight of dragons in flight and white walkers on the prowl that excites the fantasy heads, it is the show’s deep roots in “real” history that has given the show such huge crossover appeal.

There have been plenty of successful fantasy shows on the major cable networks in the last two decades of television. The staple subject matter is vampires and werewolves (“Buffy the Vampire Slayer,” “True Blood,” “The Vampire Diaries”), but successful shows have also been spun out of time travel (“Doctor Who”), Greek mythology (“Xena: Warrior Princess”) and a cryptic meditation on the potential permeability of spacetime (“Lost”).

Nothing, however, has taken the fantasy genre quite in the direction of “Game Of Thrones.” The world created by George R.R. Martin and adapted masterfully for the screen under the direction of David Benioff and DB Weiss might look on the surface like a knock-off “Lord of the Rings.” Scratch it, though, and it reveals stories borrowed from ten thousand years of human history, all bleeding together in a plot every bit as politically charged as that of “House of Cards.”...