A historian of the Iranian world in late antiquity, ca. 200–800 CE, Payne's research focuses primarily on the dynamics of Iranian imperialism, specifically how the Iranian (or Sasanian) Empire successfully integrated socially, culturally, and geographically disparate populations from Arabia to Afghanistan into enduring political networks and institutions. Also Professor Payne is deeply committeed to exploring the entanglements of the regions with East Asia, especially within and via Inner Asian contexts.