After liberating Stonebridge and Glitterdelve, the party led by the future Lady Montbarron brought the overseer reports from various people, including Gyorn, Torg, and Ella Riverstarn, filling him in on the situation with the Krug. While Yamas dealt with driving back the Krug, he sent the adventurers to find Grand Mage Merik, who was trapped within the Alpine Caverns after Goblins had stolen the Staff of Stars from him. He also told them that if they truly wanted to help the kingdom, they should reinforce Fortress Kroth, vaguely telling them that it lay beyond the caves.
It is possible that the Ibsen Yamas who appears in Dungeon Siege (set in 1144) is not the same one who is said to have defended Glacern in 1065. If they are one and the same, this would place Yamas well into his nineties at the time of the Seck Resurgence. The Overseer of Glacern may have the same name as an ancestor, just as Ibsen Yamas IV does in Dungeon Siege III.
This may also simply be a retcon in the timeline between games, as the Biography of Ibsen Yamas book in the original Dungeon Siege states that Ibsen Yamas was born in 944 and later retired to serve as Overseer of Glacern in 994.