Emperor Mark Antony appoints Herod as King of Judea, but Herod assumes control only in 37 BCE, after prevailing in war against the invading Parthians.
Mark Antony executes the leader of the Parthians, Antigonos.
Herod rises from a wealthy and influential Idumaean family. (The Idumaeans were successors to the Edomites, descendants of Esau a.k.a. Esav) in southeastern Judea/West Jordan.)
As noted above, when the Maccabeean (Hasmonean) John Hyrcanus (Hyrcanus I) conquered Idumaea in 130–140 BCE, he required all Idumaeans to obey Jewish law or leave. Most Idumaeans apparently converted to Jewish practices at that point, but not necessarily including (halachically required) circumcision by the males.
Therefore, while King Herod identified himself as Jewish and was considered as such by much of contemporary Jewish society, nonetheless according to Jewish law he technically was not Jewish. Jewish history prefers to refer to him simply as Herod the Great.
In 40 BCE the Roman senate “elects” Herod as king of the Jews. Herod is, for sure, a kindred spirit to the Roman senate: He is power–crazed and homicidal, willing to murder his own children to advance his personal glory and power.
Ironically, the Romans will 73 years later, mock Jesus with the same appellation. “King of the Jews” reads the placard placed around the neck of Jesus, as Pilate and functionaries crucify him.
In any event, matters come full–circle, with an Idumaean–neo–Jew displacing a Hasmonean as king of the Jews and of Judea. Thus, in a bizarre twist of history, while the Edomites were sidelined by the patriarch Isaac way back in biblical times, an Edomite/Idumaean ends up as ruler of the Jews.
Note that, importantly, Herod was the second son of Antipater the Idumaean, the Machiavellian manipulator of Hyrcanus II until Antipater was poisoned in 43 BCE (possibly by Herod himself).
A tax collector is pinned with the poisoning of Antipater and executed by Herod, but historians are not so sure that Herod himself was not the culprit. One would be wise not to bet against Herod being the culprit here. It would later be manifest that one of the most dangerous positions to be in was to be part of Herod the Great’s nuclear family.
In any event, Antipater, who pulled the strings behind Hyrcanus II’s rule, now exerts dominion from his grave over Judea via his son Herod.
Herod’s brother–in–law and competitor, Aristobulus III, the high priest, will mysteriously drown at a party, as well. With Herod’s father and brother both dead, Herod is free to concentrate on being Herod the Great.