It is evident to many or most Jews that the story of Purim as recited in the Scroll of Esther is basically fictional. In the first place, there is no independent confirmation of this story from any other source. In the second place, the names Esther and Mordechai are clearly derived from the names of the Babylonian pagan deities Ishtar and Marduk. And in the third place, and most importantly, the story is inherently improbable. In the entire history of the Persian empire, stretching from its establishment in the late 6th century BCE to its overthrow by the Arabs in the early 7th century CE, there is not a single recorded instance of a widespread persecution of the Jews. Persian policy was generally favorable to the Jews, starting with the decision of Cyrus, the founder of the Persian empire, to permit the Jews in the Babylonian exile to return to the land of Israel and rebuild the Temple. The Zoroastrian priests of the Persian empire did have their differences with the Jews from time to time, but these differences were never so severe as to motivate a genocidal program such as is ascribed to Haman in the Scroll of Esther.
What remains shrouded in mystery is why this fictional tale was composed and why it became a major Jewish holiday. The key to solving this mystery is to be found in the Fast of Esther. On the 13th of Adar, one day before Purim, which falls on the 14th of Adar, Orthodox Jews are expected to observe a fast called the Fast of Esther. Why is this fast held? Various reasons have been advanced, but the real reason is not difficult to ascertain. During the Maccabean period and for some time thereafter, there existed a Jewish holiday known as Nicanor Day, which was also observed on the 13th of Adar. Nicanor Day was instituted by the early Maccabean rulers in honor of the defeat of a Greek general named Nicanor by Judah the Maccabee. Nicanor, who was a general in the army of Antioches Epiphanes, had vowed to take back Jerusalem from the Jews and slaughter all the Jews he could find.
Instead he was defeated and killed by the troops of Judah the Maccabee, who then proceeded to cut off Nicanor’s head and parade it around the streets of Jerusalem. Nicanor Day was instituted in commemoration of this event, and it was a feast day, a day of feasting and rejoicing over the defeat and death of the evil anti-Semite Nicanor. We know that it was a feast day because there is an Aramaic scroll, the Megillat Taanit, dating from the 1st or 2nd centuries CE listing all the Jewish feast days, and Nicanor Day is one of them. Feast days were days on which it was not only customary to feast but on which it was specifically forbidden to fast.
Putting two and two together, it is evident that (1) the story of Purim perpetuates the essential element of Nicanor Day, the defeat and death of an anti-Semite, but (2) the Fast of Esther was designed to replace Nicanor Day and indeed obliterate it, since fasting and feasting are incompatible. This shows that the Scroll of Esther was written by someone who didn’t like Nicanor Day but still wanted to perpetuate its main theme in a fictional manner. Who could this someone have been?
Nicanor Day was instituted by the Maccabees, so most likely the author of the Scroll of Esther was someone who didn’t like the Maccabees. We know who were the main opponents of the later Maccabean rulers: they were the Pharisees. The Pharisees supported Judah the Maccabee but turned against his successors because they refused to separate the offices of King and High Priest and sought to hold both titles simultaneously. The clash between the Pharisees and the Maccabees came to a head under the rule of Alexander Jannai in the early 1st century BCE. The Pharisees supported a rebellion against Alexander Jannai, and in retaliation he executed a number of their leaders. However, in 78 BCE Alexander Jannai died, and as his sons were still too young to assume power, the kingdom of Judah was ruled for about 10 years by his widow, Salome Alexandra. Salome Alexandra reversed her husband’s policy towards the Pharisees, admitted them to the Beit Din and executed a number of the followers of Alexander Jannai who had participated in the prior execution of the Pharisee leaders. When her sons came of age, she complied with the main demand of the Pharisees and separated the offices of King and High Priest, assigning them to two different sons.
I conclude from these facts that Salome Alexandra was the real life model for the character of Esther in the Scroll of Esther. In the eyes of the Pharisees, who of course identified their cause with the cause of the Jewish people as a whole, Salome Alexandra could easily be seen as someone who had saved the Jewish people from a terrible disaster, i.e. the policies of her husband. The character of Mordechai in the Scroll of Esther would then stand for the Pharisees in general, or perhaps even one of their leaders who was close to Salome Alexandra. The idea of a Persian setting for the story was perhaps suggested by a passage in Tanach where the Persian king Artaxerxes – Ahashverosh in Hebrew or Ahasuerus in English – was said to have been approached by the Samaritans with a demand that he refuse to permit the Jews to rebuild the Temple because it would become a center of sedition against Persian rule. Artaxerxes eventually ruled in favor of the Jews. There is no hint in Tanach of any death threat against the Jews, but it is easy to see how the story in Tanach could have inspired the fictional account in the Scroll of Esther.
My guess is that a Pharisee author wrote the Scroll of Esther either during or shortly after the reign of Salome Alexandra. The context in which it was written was most likely a refusal by the Pharisees to celebrate Nicanor Day, whose glorification of the martial prowess of the Maccabees must have been closely associated in their minds with the policies of their hated enemy, Alexander Jannai. Jannai, by the way, was indeed a mighty warrior who extended the boundaries of the kingdom of Judah to their greatest extent since the days of David and Solomon. Unwilling or unable to abandon the theme of Nicanor Day altogether, the Pharisees instead replaced it with the satiric farce of the Scroll of Esther, which they celebrated one day after Nicanor Day, on which they fasted instead of feasting. So long as Nicanor Day was celebrated, this probably remained a minority approach, but after the failure of the bar Kochba revolt in the early 2nd century CE, Nicanor Day ceased to be observed by the Jewish public. It was just too nationalistic and militaristic to fit into the culture of a defeated people. Purim ended up replacing it, preserving its main theme while celebrating the virtues of guile and cunning in place of the military virtues associated with Nicanor Day.
Proof that the Scroll of Esther was not written in Persian times comes from the fact that it is the only book in the whole of Tanach to use the Babylonian names for the months. Prior to the conquest of the land of Israel by the Seleucid empire around 200 BCE the months in the Hebrew calendar were indicated only by number and not by name. The Babylonian month names, such as Adar, which are still in use today in the Jewish calendar, only came into general use in the land of Israel due to the fact that they were used in the Seleucid calendar. Some say that the use of these month names in the Jewish calendar dates from the Babylonian captivity, but the months are still indicated only by number in the books of Ezra and Nehemiah, which date from the era of Persian rule that followed the Babylonian captivity. Although the Jewish people eventually rebelled against Seleucid rule, the Seleucid calendar was nonetheless widely accepted and was used not only in the Scroll of Esther but also in the first and second books of the Maccabees. It follows that the Scroll of Esther could not have been written before 200 BCE and for the reasons already indicated was probably written towards the middle of the 1st century BCE..