Final Fantasy VII
The Gi Tribe were a group of people who waged war against the citizens of Cosmo Canyon many years before the story of Final Fantasy VII. At the time, Nanaki was only a puppy and it was the role of his parents to try and ward off the Gi Tribe's advancing forces.
Seto hatched a plan which would ultimately see the Gi Tribe defeated, as he lured them into a cave, which was sealed behind him. He knew that by doing this, he would perish eventually, but the sacrifice had to be made in order to protect his family and the village.
The Gi were unrelenting and viciously attacked Seto using poisonous darts. He fought as long as he could, but succumbed to the petrification and was eventually turned to stone.
The Menace Still Lingers
Bugenhagen unlocks the Cave of the Gi when he feels it is time for Nanaki to learn the truth about his father. Inside he fights against various undead versions of the Gi Tribe, who are still lingering around.
Before reaching his father, Nanaki is forced to fight against the leader of the Gi Tribe, Gi Nattak. With his defeat, the Gi Tribe fades away and becomes a distant memory and Nanaki is able to see his father in a whole new light.