Brenda Shaffer in The National Interest
Exactly how ethnically diverse Iran actually is, however, is a matter of some debate. There are currently “no agreed-upon academic or governmental sources on Iran’s ethnic make-up,” says Brenda Shaffer of Georgetown University, one of the country’s leading experts on Iran’s ethnic minorities. And because there aren’t, U.S. government estimates—including the CIA’s vaunted World Factbook, which policy institutes and academia routinely rely on for figures—have tended to reflect official Iranian data regarding the population of its provinces.