The politics and socio-economics of Palestine
After Pompey's conquest of Palestine, Judaea (as the province was called) retained some form of self-government. The high priest, Hyrcanus, was allowed some civil authority, but his territory was much reduced. However, the politics of Judaea was influenced by power struggles between four groups. There were the supporters of two brothers of the Hasmonean dynasty, Aristobulus II and Hyrcanus II, both of whom competed against each other and against Rome for power over Judaea. Then there were religious leaders seeking the abolition of Judaean kingship and rather government by the temple institution. Finally, there was the family of Antipater, an influential family with Arabian connections.
To quell the turmoil, the province was divided into five administrative councils whose membership was made up of aristocratic families (of priestly or of Hasmonean origins). This created the impression of self-rule. However Antipater recognised that the Romans were interested in alliances - forms of self-rule that would recognise Roman superiority. The family of Antipater, especially his son Herod, actively sought Roman support for some form of acceptable independence. As a result of this, these family members came into prominence: Herod was appointed king (technically) of Judaea in 41 BCE, and after he had repelled a Parthian invasion and defeated Aristobulus II and his supporters, he became king in reality in 37 BCE. Herod ruled until his death in 4 BCE and his family continued to play an important role in the political world of the Roman Empire until the end of the first century.
Herod ruled Judaea as a client king (or friendly king) of Rome. Client kings were not uncommon during the early part of the Roman Empire. Client kingship was useful to the Romans because the client kingdom served as a buffer to the areas not under Roman control and could be called upon to render military aid when needed. This was particularly convenient with regard to Palestine, as the Persian Empire was Rome's major rival in the eastern parts at the time (Rome and Persia being the two ‘world powers’ of the period).
Client kingship was, furthermore, useful, as Rome did not have to expend valuable resources in administration and the posting of legions on a permanent basis, because the client kingdom took care of its own administration and defence of its borders under normal circumstances.