When Simba and Nala were cubs, they made it past Zazu to reach the Elephant Graveyard, surrounded by elephant's skulls, bones and old geysers. They took a look around before they went inside the biggest elephant skull when Zazu came to stop them. He told them the Elephant Graveyard is too dangerous and Simba laughed about it when he thought of its danger. When three hyenas, Shenzi, Banzai, and Ed came and surround them and afterward began to chase them suddenly Simba and Nala were trapped at the walls and Simba tried to roar to protect Nala, but the Hyenas were laughing and teasing him. Simba gave another roar and it sounded like the noise of an adult lion's roar. It was Mufasa, who came to rescue the cubs and he told the Hyenas to never go near his son again and they ran away after that.
He was disappointed that his son disobeyed him and took the cubs back home to the Pride Lands. Later that night, Scar told his henchmen he had a plan to murder Mufasa and Simba for good to take over the throne.
Years later, after Mufasa is killed, and Simba runs off into exile from the Pride Lands, the hyenas, (who are now living at Pride Rock under the reign of Scar) begin to lose their faith in Scar. Once Simba returns as an adult and defeats Scar, they betray and kill their master, before being engulfed in a fire that broke out during the fight via one strike of dry lightning.
Now the graveyard is abandoned by the hyenas, as many of them are burned alive in the fire, whilst others run away from the Pride Lands, not returning to the wasteland, leaving it dormant of hyenas. Their descendants, led by Janja live in the Outlands, which strides along the borders of the Graveyard and the Pride Lands.