【新刊紹介】Catherine HOLMES and Naomi STANDEN (eds.), The Global Middle Ages, Oxford, Oxford Academic, 2018; Johannes PREISER-KAPELLER, Lucian REINFANDT, and Yannis STOURATIS (eds.), Migration Histories of the Medieval Afroeurasian Transition Zone: Aspects of Mobility between Africa, Asia and Europe, 300-1500 C. E., Leiden-New York, Brill, 2020; Erik HERMANS (ed.), A Companion to the Global Early Middle Ages, Leeds, ARC Humanities Press, 2020