'Year of' in the Bible

in the third year of his reign, he made a feast to all his rulers and his servants, the power of Persia and Media, the ranking men and rulers of the provinces, being before him

So Esther was taken to king Ahasuerus into his royal house in the tenth month, which is the month Tebeth, in the seventh year of his reign.

In the first month, which is the month Nisan, in the twelfth year of king Ahasuerus, they cast Pur, that is, the lot, before Haman from day to day, and from month to month, [to] the twelfth [month], which is the month Adar.