At the peak of Qi Gatherer, the world’s Yuan Qi would transform the body, and rejuvenate a person, resulting in him reaching a brand new state–Purple Blood.
Strictly speaking, the Purple Blood level was the true beginnings of martial arts training.
When a warrior cultivates his body to a certain stage, his body will undergo changes. The moment he breakthroughs into the Purple Blood Warrior realm, all his blood will become as heavy as mercury. This blood would appear golden purple in the sun.