Nothing restrained their tyranny but such sense of right as they might happen to possess, and the fear of removal or execution if the voice of complaint reached the monarch.
Besides this uniform civil administration, the Empire was pervaded throughout by one and the same military system.

The services of the subject nations as soldiers were, as a general rule, declined, unless upon rare and exceptional cases.

Order was maintained by large and numerous garrisons of foreign troops--Persians and Medes--quartered on the inhabitants, who had little sympathy with those among whom they lived, and would be sure to repress sternly any outbreak.

All places of much strength were occupied in this way; and special watch was kept upon the great capitals, which were likely to be centres of disaffection.
Thus a great standing army, belonging to the conquering race, stood everywhere on guard throughout the Empire, offending the provincials no doubt by their pride, their violence, and their contemptuous bearing, but rendering a native revolt under ordinary circumstances hopeless.
Some exceptions to the general uniformity had almost of necessity to be made in so vast and heterogeneous an empire as the Persian.

Occasionally it was thought wise to allow the continuance of a native dynasty in a province; and the satrap had in such a case to share with the native prince a divided authority.