and finally the satrapy of the Indians, which included all the tribes on the right bank of the Indus, from the summits of the Himalayas to the junction of the Cabul and the Indus (the twentieth).[347] The viceroys whom Darius placed over these districts had to keep the aggregate of the various political bodies, of which the satrapies consisted, in obedience to the empire and in peace towards each other; to collect the taxes and tribute, to summon and organize the military levies. The satrap was the highest authority in his province--the supreme appeal in law, administration, and military affairs. The king alone was superior. He was the judge before whom could be laid appeals from the judgment of the princes and local boards, if the claimant had not preferred to go to him in the first instance; he was the only judge between the princes, the districts, the tribes and cities of his province. His arrangements must be obeyed. He was to take measures for the advancement of cultivation and the increase of the population in his province, both as fullfilling the rules of the Avesta, and in the interest of the kingdom. He kept watch over trade and currency, over the military roads, the stations, the harbours, the canals and dams; he had the right to strike silver coins for his province. He had charge of the military affairs of the province; and was responsible for the weapons and ships when required for the levy. The apportionment of the taxes and tributes to the districts and communities of the province, the collection of these, and the despatch of the proper revenues to the king were among his duties. He had royal scribes to assist him in these matters, who read to him the commands of the king and drew up his reports to the king. It was not likely to escape Darius that the great powers in the hands of the satrap would lead him to use his delegated power independently and even against his chief. The attempt of Oroetes to found an independent monarchy in Asia Minor, had caused him great anxiety in a time of difficulty. He could not always expect that such tendencies in distant provinces could be known in time, or that rebellions on the part of satraps could be prevented. The king withdrew from them the nomination of the commanders of the castles, which controlled the main roads of the provinces, the more important fortresses and citadels of the provinces, _e.g._ the citadels at Ecbatana, Babylon, and Memphis, that, as Xenophon says, "a satrap who trusting to his power and the number of his subjects should refuse obedience, might find opponents in his province"; and he even nominated the commanders of the Persian battalions, which formed the garrisons of the fortresses,[348] but limitations of this kind were insufficient against the power which their office gave to the satrap, if the royal power was unable to make itself felt with force and rapidity. The central power must be in vigorous operation against the satraps, if the