The epic begins by recounting the story of Jangar's great-grandfather, Tahil Zul Khan, who is kind and honest.
Tahil Zul Khan leads his people to a land called Bomba where he hoped to create a place where they would be no suffering or death.
However, one day Tahil Zul Khan goes to check on his horse herd and a blizzard strikes, forcing him to take refuge in a valley.
Also noted for being kind and wise, he tries to do what his father has done, but is thwarted by years of bad weather that kills half the tribe's livestock.
His advisor, Master Choirom, suggested that he take a wife, and mentioned a 16-year-old girl named Urmaa in the tribe of Dorj Khan in the south.
In accordance with custom, the other members of Urmaa's family playfully tried to stop him, and he had to force, argue, and persuade his way through to the bride's yurt.
The couple secretly stole out to the steppe and hid behind a large rock so that they could watch a stallion and mare mate.
The child was strong and kicked his leather swaddling cloths to pieces, making Urmaa afraid that her son was ill-fated to cause destruction.
Seeing Ujung Aldar's weakness, he attacked with 10,000 warriors on black horses and easily captured Bomba.
The servant took the child to Big Black Mountain and hid him in a cave, then walked back to the palace to see what had happened.
Discovering everything destroyed and the Khan dead, he decided to take his revenge by attacking some of the invaders as they sat around a fire.
In the mountain cave, the boy sucked the white jade to keep himself from growing hungry or thirsty for a few days.
A man named Mengen Xigxirge was hunting nearby, and he noticed the horse Aranjagaan grazing.
At first Mengen Xigxirge wanted to adopt the boy, so he decided to give him the name "Jangar."
Three-year-old Jangar fought his way to Goljing's palace, destroying three strongholds on the way, and thrust his spear into the Manggus' chest, killing him.
Meanwhile, another ruler named Shar Durdeng began raiding the outskirts of Bomba for livestock, women and children.
Taking hold of the intoxicated Shar Durdeng, Jangar threw him off his throne, and proceeded to break ribs and spinal bones until Shar Durdeng agreed to leave Bomba in peace and pay taxes and tribute.
Hearing of Jangar's success, Mengen Xigxirge was sorry that he left the boy alone on the mountain unharmed.
But Mengen Xigxirge's son Hongor grabbed hold of Jangar and pleaded his father not to harm him.
Jangar, riding Aranjagaan and carrying the Aram spear, went to attack Altan Gheej.
In 2014, the Jangar Culture and Art Palace (江格尔文化艺术宫) was opened in the Hoboksar Mongol Autonomous County, in Xinjiang (China), which is traditionally considered the place of origin of the epic.