"This is a book about Eurasian empires and their spatial dimensions. Which factors prompted the empires' expansion causing some of their leaders to embark on ever more costly wars at the remote frontiers? Which factors, conversely, put limits to this expansion? How did the builders and custodians of major empires conceive of their space? And what measures did they take to integrate this vast space into a coherent political entity? To what extent were the empires' expansion and contraction influenced by common factors - from ecology to ideology, from military and economic considerations to the nature of the ruling elite? How did these distinct factors influence the trajectories of individual empires?"--