'Reign' in the Bible

in the third year of his reign he provided a banquet for all his officials and his servants. The army of Persia and Media was present, as well as the nobles and the officials of the provinces.

Then Esther was taken to King Ahasuerus at his royal residence in the tenth month (that is, the month of Tebeth) in the seventh year of his reign.

In the first month (that is, the month of Nisan), in the twelfth year of King Ahasuerus' reign, pur (that is, the lot) was cast before Haman in order to determine a day and a month. It turned out to be the twelfth month (that is, the month of Adar).