I Am the Invincible Swordsman

In the mysterious ancient Eastern country of China, there is a mountain called Tianshan. In the Tianshan Mountains there is an unknown sect called Tianmen. In the sect there is a mysterious old man and a boy whose life experience is a mystery. In this era of invasion by alien species, let's see how the little boy punishes the evil, turns evil into good, and walks out on his own path.