The foundational circle was something he had learned from his clan's old friend, Alchemist Ma Bo, the guest teacher from the Jade Dao Leaf Imperial Academy.
He was the one who coined the term as he and the rest of the Yang clan members were refining their body refinement techniques.
Body refinement was a complete evolution of the cultivator from a cultivator. Everything that constituted the body had to be worked on, no part could remain neglected especially if one had the hopes of reaching the gold body, the diamond body, and the peerless jade physique stage.
The ingredients used had to match the user's body, the user had to extract every benefit completely from said ingredients, and to finally ensure that they could grasp their abilities, their mind, soul, and willpower had to be elevated to match their body's progress.
Not one aspect could be missed or there would be an imbalance.