Talk to the 100 Year Old Wise Man and learn about the Evil Pigs and its origins.
The event will be activated in the beginning of the game when the citizen talks to Tomba. In order to complete this event, the Clear the Fog event needs to be done.
Work your way through the Forest of All Beginnings until you reach some climbable walls at the right side of the area. Go up and turn left to find the 100 Year Old Hut. Enter it and talk to the 100 Year Old Wise Man.