In the course of reviewing John Dominic Crossan’s Jesus and the Violence of Scripture A. N. Wilson explains the one key aspect of the context of the Salome story:
When Herod Antipas moved the capital of Galilee from Sepphoris to the new foundation of Tiberias, he was doing so as an act of sycophancy to Tiberius. He was involved in a commercialization of the Galilean lake monopolizing the fish trade and hugely increasing the taxes. That was to impress the Romans, but to appease his Jewish subjects he divorced his Arab wife and married his Hasmonean sister-in-law Herodias, who had herself to divorce her husband who happened to be Antipas’s brother. John the Baptist denounced this, and famously paid for it with his head. 
Wilson, A.N. “Two Horses,” Times Literary Supplement (9 December 2015): 27.
Last modified 7 February 2016