In the last years of the reign of King Sendar the Sunpriests of Karse hired the Tedrel Nation, half a nation of homeless mercenaries that not even the Mercenary Guild wouldn't back since they refused to obey any of the normal rules that bonded Mercenary Companies adhered to, such as; no raping, pillaging or outright destruction of infrastructure and population, to fight Valdemar for them, promising the land held by Valdemar to them as a new homeland. The Tedrel Wars lasted a little over four years with the first three beginning around spring and ending in autumn, making sure to keep Valdemar on the defensive and as was stated in Exile's Honor:
"These were not battles, these were wars— where the Tedrels moved into land opposite the Border, fortified it, then launched campaign after scorched-earth campaign from spring through autumn and then vanished, only to pick and fortify a new spot during the winter from which to pillage a new territory. Each time they did this, they effectively halted all farming, all commerce in that area, decimating it and leaving it barren and trying to recover. It was a diabolical plan, and there was nothing that Valdemar could do to thwart it without crossing the Border into Karse themselves, which Sendar (wisely) would not allow."
During the last year of the war the Tedrel's were routed after a pitched battle but at perilously high cost, the king of Valdemar, Sendar, his Companion, as well as the Monarch's Own Companion, Taver, were killed, leaving the heir Selenay as Queen and Talamir near death's door, desperately wanting to follow his Companion. The Valdemaran army managed to send what was left of the Tedral forces fleeing, Most back into Karse some into Valdemar itself and left them to it, knowing that they would either settle into a new life (in Valdemar) or show themselves to the authorities and likely end up at the end of a hangman’s noose for any more trouble they caused.
As for those that fled into Karse, considering that they'd managed to force the Karsites to practically empty their treasury in order to hire the Tedrels, their own forces were guaranteed to take care of the rest. As a footnote to the war, Alberich managed to take a small force just inside the Karse border to rescue what were dubbed the Tedrel Orphans, a motley group of just over a thousand children, camp followers and assorted others and bring them back over the border to safety.