For almost three centuries, until 612 BC, the small kingdom of Assyria dominated the Middle East, its empire at one point extending from Iran to Egypt. The story of those years - the triumphs of the Assyrian kings in war and peace, their exploits in the hunting field, and the gods who watched over them - were recorded in stone on the walls of a succession of royal palaces. These sculptures, offering eye-witness views of a long-lost civilisation, were...