Heaven on Earth by Richard Landes

This is the first chapter of a systematic and thorough book on millenial ideas and movements.  Landes, whose work I have been following for nearly 30 years, says the following in his listing at Academia.edu:

Medieval historian specializing in the apocalyptic movements of the year 1000, more generally the "longue durée" of millennialism (heaven on earth). Began my career by studying a major forger ca. 1000 (Ademar of Chabannes), and shifted when I discovered a major forgery of 2000 (Muhammad al Durah). Currently following the interaction between two apocalyptic movements - progressive left (arc of history) and Caliphaters (Muslims who believe the global caliphate is coming in their lives).

Other chapters may be found at Academia.edu.

Image:  Otto III, the Roman/German/Greek of the Year 1000