Complex sentence: It has also been attributed to the Zealot factions which had wrested control of the Temple Mount and fortified it prior to its fall, some of which continued to hold out in Jerusalem's Upper City for a month after the city had been breached by the Romans.
Split into simpler sentences: It has also been attributed to the Zealot factions which had wrested control of the Temple Mount and fortified it prior to its fall. Some of these continued to hold out in Jerusalem's Upper City for a month after the city had been breached by the Romans.