What the empire was not was a unitary nation-state or a mighty empire in the 19th-century manner.
Times, Sunday Times
Both oracles replied that if he did so, he would most certainly destroy a mighty empire.
The Times Literary Supplement
Could war or invasion have proved the undoing of this once mighty empire?
Times, Sunday Times
He had indeed destroyed a mighty empire: his own.
The Times Literary Supplement
Both were once mighty empires.
Times, Sunday Times