'Reign' in the Bible

The Levites in the days of Eliashib, Joiada, and Johanan, and Jaddua, were recorded chief of the fathers: also the priests, to the reign of Darius the Persian.

While all this was happening, I was not in Jerusalem, because I had returned to King Artaxerxes of Babylon in the thirty-second year of his reign. It was only later that I asked the king for a leave of absence