For the better collection of tribute, twenty provinces were created, governed by twenty satraps.

Hitherto no specific and regular tax had been levied, but the Persian kings had been contented with reluctant presents, or arbitrary extortions.

Darius now imposed a limited and annual impost, amounting, according to the computation of Herodotus, to fourteen thousand five hundred and sixty talents, collected partially from Africa, principally from Asia [41].

The Persians, as the conquering and privileged race, were excluded from the general imposition, but paid their moderate contribution under the softer title of gratuity.

The Colchians fixed their own burdens--the Ethiopians that bordered Egypt, with the inhabitants of the sacred town of Nyssa, rendered also tributary gratuities--while Arabia offered the homage of her frankincense, and India [42] of her gold.
The empire of Darius was the more secure, in that it was contrary to its constitutional spirit to innovate on the interior organization of the distant provinces--they enjoyed their own national laws and institutions--they even retained their monarchs--they resigned nothing but their independence and their tribute.