Second Toa-Dark Hunter War

Cause of War
Shortly after the war on Metru Nui between the Toa and Dark Hunters, the Shadowed One, still bent on conquerig Metru Nui, went to the Southern Continent himself to get the Mask of Life, which he planned to use against the Toa army. In response, Lhikan sent the Toa who survived the war to protect the Mask, and the Shadowed one launched his Dark Hunters against them.

Toa Mangai in the War
Among the Toa in the War, four Toa Mangai of Ice and Naho, Toa Mangai of Water were all in the war. They were all taken prisoner in the war by Nidhiki, who had mercy on his old allies, and brought to Odina, and were presumed to have died in combat. In reality, they were brought to Xia when the Dark Hunters moved there, and remain there to this day. As a result, they survived when Teridax posed as Dume.

The Piraka
The future six Piraka all fought in the war, ad had heard rumors about the Ignika while fighting. This is why, when Teridax sent them after the Mask, they didn't question it's sudden appearance in their minds and passed it off as a memory.