King Ahasuerus had a competition of women to replace his previous wife because she was very rebellious towards him. Mordechai told his cousin Hadasah/Esther to enter the competition but asked her not to reveal her race. She won the heart of the King and later Ahasuerus, the King of Persia was persuaded by his minister, Haman of Macedonia (Greeks) to destroy all the Jews in his kingdom which stretched from India to Ethiopia.
This day of destroying the Jews was chosen by Pur meaning lots cast by Haman hence the feast is called Purim.

Esther 9:

v24- Because Haman the son of Hammedatha, the Agagite, the enemy of all the Jews, had devised against the Jews to destroy them, and had cast Pur, that is, the lot, to consume them, and to destroy them;

The king’s wife was Esther a Jew of the tribe of Benjamin remember she had been instructed by her cousin Mordechai to keep her nationality a secret until the time came to reveal it. Queen Esther with the help of Mordechai confounded and ended Haman’s plot and saved the Jews.

In the Apocrypha; Esther 16:

v10- For Aman, a Macedonian, the son of Amadatha, being indeed a stranger from the Persian blood, and far distant from our goodness, and as a stranger received of us,

v11- Had so far forth obtained the favour that we shew toward every nation, as that he was called our father, and was continually honoured of all the next person unto the king.

v12- But he, not bearing his great dignity, went about to deprive us of our kingdom and life:

v13- Having by manifold and cunning deceits sought of us the destruction, as well of Mardocheus, who saved our life, and continually procured our good, as also of blameless Esther, partaker of our kingdom, with their whole nation.

v14- For by these means he thought, finding us destitute of friends to have translated the kingdom of the Persians to the Macedonians.

Esther 9:

v27- The Jews ordained, and took upon them, and upon their seed, and upon all such as joined themselves unto them, so as it should not fail, that they would keep these two days according to their writing, and according to their appointed time every year;

v28- And that these days should be remembered and kept throughout every generation, every family, every province, and every city; and that these days of Purim should not fail from among the Jews, nor the memorial of them perish from their seed.

v29- Then Esther the queen, the daughter of Abihail, and Mordecai the Jew, wrote with all authority, to confirm this second letter of Purim.

Shalom