Alma 59:1

Now it came to pass in the thirtieth year of the reign of the Judges over the people of Nephi, after Moroni had received and had read Helaman’s epistle, he was exceedingly rejoiced because of the welfare, yea, the exceeding success which Helaman had had, in obtaining those lands which were lost;

It was year 30 that judges ruled over the Nephites. Moroni got a letter from Helaman and read it. He was very happy because Helaman had done so well. He had gotten back the lands that were lost.

In the thirtieth year of the judges, Moroni received Helaman’s letter and was thrilled by the news. Helaman had been incredibly successful—he’d retaken all the lands they’d lost.