Once a quiet mountain surrounded by lush, fertile land, Mok'gram erupted in Year 425 when Arth descended to the core of Ilisara to try and destroy it using one of Esk's Tears made for the orcs. Arth allowed himself to be a conduit for Vandun's power, but the legendary gemstone shattered under the intense heat, pressure, and radiation of Ilisara's core. Arth's body was destroyed, and his spirit was evacuated by Vandun. The resulting explosion from the orc legendary gemstone resulted in the eruption of Mok'gram and left Arth without a body to inhabit.
Mortals are generally unaware of the godly origins of Mok'gram's eruption.
After the mountain spewed lava across half the land and covered Ilisara in clouds of ash that didn't recede for years, most of Isandor become a wasteland. Only the jungle and bog area in the south and the woodland in the north remained relatively untouched. It took many years, but plants eventually sprung up from Mok'gram's mineral-rich soil and restored some of the area to its lush green beauty. This area, a tiny place where farming and food production were possible, came to be known as Thes.
For a time, the orcs suffered greatly. Their population could not be sustained by the meager land left to farm and hunt. Many of them died off after the fallout from Mok'gram's eruption. Sacrificial killings were done to keep the population under control and to appease Arth. By Year 500, the orcs had formed into organized clans led by Orcish Warlords and began assaulting Hellan, attempting to take over the much-needed land for their hungry, growing population.