From the introduction:
Link, the Hero of Hyrule, adventures across the land, his journey complete, Agahnim defeated, and his princess saved. What more is there for him to do but wander? As he travels, he comes across a shrines, containing what appears to be the mythical Triforce. As he approaches, he hears a scream. As he touches it, the Triforce teleports him to the far away land of Labrynna.