For millennia much of the world was ruled by emperors: a handful of individuals claimed no limit to the lands they could rule over and no limit to their authority. They operated beyond normal human constraint and indeed often claimed a superhuman or divine authority. In practice they ran the gamut from being some of the most remarkable men who ever lived, to being some of the worst and least remarkable.

Dominic Lieven's marvellous new book, In the Shadow of the Gods, is the first to grapple seriously with this extraordinary phenomenon. Across the world peoples, willingly or unwillingly, fell into orbit around figures who reshaped or destroyed entire societies, imposed religions and invaded rivals. Lieven describes the anatomy of imperial monarchy and the principles by which it functioned. He compares the great emperors of antiquity, the caliphs and the warrior-emperors of the steppe before he turns to the Habsburg, Russian, Ottoman, Mughal and Chinese emperors, packing the book with extraordinary stories, astute observations and a sense of both delight and horror at these individuals' antics. The entire breadth of extreme human behaviour is here - from warlords to patrons of the arts, from political genius to feeble incapacity and pathological violence.

As one of the great experts both on empires and on Russian history, Lieven is brilliantly qualified to write a book that brings to life a system of rule that dominated most of human history, as well as some of history's grandest and most dismaying figures.