The subject, naturally, is Genghis Khan and the moral depravity that is often a characteristic of transformative world leaders. The voice begins.

"Would you be willing, under certain conditions, to order the killing of an innocent woman or child, or old person?" the voice wants to know. If you said that you would not be willing to do that," it continues, "you are already off the potential great person list." It pauses for a couple of seconds.

"At least in terms of world leaders."

The gravelly, conspiratorial baritone belongs to Dan Carlin, a 49-year-old former talk radio personality who has achieved superstardom in the brightening firmament of podcasting . On his show "Hardcore History ," Carlin singlehandedly narrates epochal events of the last several thousand years (World War I , The Black Death, the Norman invasion of England and the rise of the Khans , to name a few). Recorded from a studio in his home in Eugene, Oregon, the show hasnt exactly gained household name status on the order of "Serial," the true-crime narrative that catapulted the medium into the mainstream last year.

But "Hardcore History" is firmly ensconced in the upper reaches of iTunes most-downloaded list (No. 9 as of this writing), sharing coveted real estate with public-radio mainstays like "Fresh Air" and "This American Life" and long-established boldface names like Marc Maron and Adam Carolla.

Listen to Dan Carlin's thoughts about his podcasts, the future of warfare, and where he thinks America is headed below:

Audio feature produced by Katelyn Bogucki and edited by Nick Offenberg

Unlike most popular podcasts, Hardcore History has no guests, no interviews and no recorded segments. Its not a marvel of audio engineering like "Radiolab," nor does it benefit from a constantly rotating cast of characters like The Moth. Its just Dan Carlin talking to you -- and hes a damn good talker.

A virtuoso orator with a masters feel for the rhythm of language, Carlin layers his winding sentences with conversational asides (on the Mongols indefensible violence: "lemme tell you why it puts me in a weird position Im a fan of these people!"), piquant scene-setting (on the unspeakable horror at the Battle of Verdun during World War I: "This is Mordor"), artfully posed hypothetical questions and lots of pregnant pauses.

"He uses the medium about as well as anybody," said Adam Sachs, who runs Midroll Media, the parent company of the popular Earwolf podcast network (which is not connected with Carlin). "He really demonstrates the undeniable power of a riveting story."