Long ago, when the Mongols ruled over China, a rebellion arose among the Chinese, who not only assassinated the Mongol king but also conspired to annihilate his lineage.

The queen, with the help of a monk, managed to escape with her infant son, the heir to Genghis Khan’s legacy. They fled in haste, pursued relentlessly. As they approached the Zagastain Pass, their pursuers drew dangerously close. The shouts of the Chinese soldiers, eager to claim the hefty reward for capturing the escapees, echoed behind them. Exhausted, the monk collapsed and passed away as they reached the peak of the pass.

In desperation, the young queen lifted her son skyward and cried out:
“Dear Mother Earth of Mongolia, gods above! Protect the descendant of the great man who made the name of Mongolia resound across the world. Spare the flesh and blood of Genghis Khan from death!”

Suddenly, a small white mouse appeared beside her and, in a calm, human-like voice, said:
“I have been sent to rescue you. Fear not and continue your journey. Great fame awaits your son, while death and misfortune are destined for your pursuers.”

The queen looked at the mouse in disbelief and asked, “How can a tiny creature like you possibly defeat 300 horsemen?”

At that moment, the heavens roared with thunder, and lightning struck. A massive rock on the mountain shattered, tumbling down the pass and crushing the pursuing soldiers beneath it. The little mouse then climbed atop the boulder and declared:
“I am the guardian spirit of Zagastain. I am powerful and protected by the gods. However, since you doubted my strength, the Zagastain Pass will, from this day forward, bring obstacles not only to sinners but also to the righteous.”

From that time on, travelers have regarded the Zagastain Pass with awe and fear. The pass, characterized by its steep cliffs and a river running below, remains a challenging route. Yet it is an essential path for those journeying to the provincial center of Zavkhan, Uliastai.