Phraates sent four of his sons as hostages to Rome. But the Roman protectorate over Armenia was by no means permanent; its supporters had soon to give way to the Parthian party. Gaius Caesar between 1 B. C. and 2 A. D. restored Roman influence, but again the Parthians got the upper hand and held it until 9 A. D., when Phraates was overthrown and was succeeded by one of his sons whom Augustus sent from Rome at the request of the Parthians. *Judaea and Arabia.* To the south of the Roman province of Syria lay the kingdom of Judaea, ruled by Herod until his death in 4 B. C., when it was divided among his sons. Subsequently Judaea proper was made a province administered by a Roman procurator. To the east of the Dead Sea was the kingdom of the Nabataean Arabs, who controlled the caravan routes of the Arabian peninsula and who were firm Roman allies. With their aid a Roman army under Aelius Gallus in 25 B. C. sought to penetrate into the rich spice land of Arabia Felix, but suffered such losses in its march across the desert that it was forced to return without effecting a conquest. At the same time Gaius Petronius defeated the Ethiopians under Queen Candace and secured the southern frontier of Egypt. Through the ports of Egypt on the Red Sea a brisk trade developed with India, from which distant land embassies on various occasions came to Augustus. Further west in Africa, Augustus added the kingdom of Numidia to the province of Africa, and transferred its ruler, Juba II, whose wife was Cleopatra, daughter of Antony the triumvir, to the kingdom of Mauretania (25 B. C.). The conquests of Augustus established in their essential features the future boundaries of the Roman Empire. At his death he left it as a maxim of state for his successor to abstain from further expansion. VI. THE ADMINISTRATION OF ROME *The problem of police.* One of the great problems which had confronted the Roman government from the time of the Gracchi was the policing of Rome and the suppression of mob violence. To a certain extent the establishment of the praetorian guard served to overawe the city mob, although only three of its cohorts were at first stationed in the city. As a supplement to the praetorians Augustus organized three urban cohorts, each originally 1500 strong, who ranked between the legionaries and praetorians. Between 12 and 7 B. C. the city was divided for administrative purposes into fourteen regions, subdivided into 265 _vici_ or wards. Each region was put in charge of a tribune or aedile. A force of six hundred slaves under the two curule aediles was formed as a fire brigade. But as these proved ineffective in 6 A. D. Augustus created a corps of _vigiles_ to serve as a fire brigade and night watch. This corps consisted of seven cohorts, one for every two regions, and was under the command of an equestrian prefect of the watch (_praefectus vigilum_).