Year 170 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Mancinus and Serranus (or, less frequently, year 584 Ab urbe condita). The denomination 170 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Antiochus IV decides to let Ptolemy VI continue as king of Egypt, but as his puppet. He does this to minimise any reaction from Rome towards his invasion. Antiochus IV then departs Egypt to deal with disturbances in Palestine, but he safeguards his access to Egypt with a strong garrison in Pelusium.
With Antiochus IV now absent from the country, the citizens of Alexandria choose Ptolemy VI's brother Ptolemy VIII Euergetes II as their king. The two Ptolemy brothers agree to rule Egypt jointly with their sister Cleopatra II and Coele Syria is invaded by the Egyptian forces.
The usurped high priest of Judea, Jason, does not abandon his claims to being the high priest which he has lost to Menelaus two years earlier. While Antiochus IV is waging war against Egypt, he succeeds in making himself master of Jerusalem once more and forces Menelaus to seek refuge in the citadel.