The Sasanian Empire (3rd-7th centuries) was one of the largest empires of antiquity, stretching from Mesopotamia to modern Pakistan and from Central Asia to the Arabian Peninsula. This mega-empire withstood powerful opponents in the steppe and expanded further in Late Antiquity, whilst the Roman world shrunk in size. Recent research has revealed the reasons for this success: notably population growth in some key territories, economic prosperity, and urban development, made possible through investment in agriculture and military infrastructure on a scale unparalleled in the late antique world....