Wuxia tale, totally UNoriginal: Guess which country is this tale actually from?

I wanted to illustrate that yes, Eastern and Western tales aren't so far apart. To this goal, I wrote my own wuxia tale. Here it is... Can you guess which tale am I re-telling, wuxia-style?
It doesn't count if you already knew the answer!

"There was Li, the son of a farmer, was born in his village. Due to serious illness in his youth, he was unable to walk until the age of 33. He could only lie on a Northern oven, gathering Yang energy, until he was miraculously healed by two pilgrims. Then, secure in his amassed Yang energy which he now could use to fight and not to prolong his life, he went on to challenge the wandering xia known as the Sacred Mountain.
Turned out, the Sacred Mountain was almost a mountain in his own right! Albeit sleeping, he was a master of Golden Bell and remained unhurt from Li's attack, after Li went to hit him with his iron rod. Instead, he grabbed Li and put him in his pocket, so he could finish his sleep.
After awaking, they talked and became friends. But they only wandered so long together: Li and Sacred Mountain found a coffin, and it was a giant stone coffin! Both had a premonition, with celestial spirits and dragons descending from Heavens to imply that it is for Sacred Mountain. But what would a living man need a coffin for?
Li managed to lie down in the coffin first, but it was too large for him. It did, however, fit Sacred Mountain perfectly. When the giant xia closed the lid, it sealed to the coffin. Before it sealed completely, however, he did manage to infuse his breath with part of his powerful Chi, and give it to Li. His breath was the only part of him that could still leave the coffin!
Li went on to serve prince Wan the Fair Sun. Along the way he single-handedly defended a city from nomadic invasion and was offered honours by the local ruler, but Li declined to stay. In the forests, he killed the forest-dwelling monster Nightingale the Robber, who could stun or even murder travellers with his powerful whistle! The monster was a heterodox monk who, in emulating the Chi of birds, had developed partial bird like features! On one hand, he was able to fly, on the other, despite having a human family, he lived in a nest, and received drinks with his hands.
Nightingale the Robber was said to live in a forest and would sit in a tree by the road to Beijing, and stun strangers with his powerful whistle. He was recognised by his scream, "All the grasses and meadows become entangled, the azure flowers lose their petals, all the dark woods bend down to the earth, and all the people there lie dead!"
It was a mighty battle! Nightingale the Robber levelled half the forest - but he was defeated by Li by his thrown daggers, who struck him in the eye and temple, then dragged the defeated villain to Wan. He wished to hear Nightingale the Robber whistle, but the creature claimed he was too wounded to whistle. Nightingale the Robber requested wine to drink so that his wounds would disappear, then he would whistle for the prince. When he whistled all of Wan's palaces were destroyed and many lay dead. After this, Li took Nightingale the Robber into an open field and cut off his head.
In Kiev, Ilya was declared Wulin Senior, Hero of the army, by the Prince. He defended his country from numerous attacks by the steppe people, including the Golden Horde's chief. Generous and simple-minded but also temperamental due to his excessive Yang, Li once went on a rampage and destroyed all the pagodas in Beijing, after Prince Wan failed to invite him to a celebration. He was soon appeased when the prince sent for him, though."


The answer would be given in the comments, if anyone comments.