'Year' in the Bible

In the third year of his reign, he gave a banquet for all his officials and ministers, and the military leaders of Persia and Media, the nobles, and the provincial officials were present.

Esther was taken to King Ahasuerus to his royal palace in the tenth month, which is the month Tebeth, in the seventh year of his reign.

In the twelfth year of the reign of King Ahasuerus, in the first month (the month Nisan), the (that is, the lot) was cast in Haman's presence to determine the best day and month to carry out his plot. The lot indicated the twelfth month, the month Adar.

establishing that they should celebrate the fourteenth and fifteenth days of the month Adar every year,

the Jewish people established this celebration, making it a tradition for themselves, for their descendants, and for all who joined with them that they should not fail to observe these two days each year, based on the written instructions, and at the prescribed time.