When the Lord of Stone God Palace attained the Dao and ascended all those years ago, he had not gone to any of the other blood demon worlds, but had come to the Heaven of Freely Enjoying Others' Emanations.
He had refined all his spirit and blood into a streak of bloodlight and flown straight here.
The Blood God Scripture was wondrous beyond measure. The Buddhist Sect refined the mind, and the Mystic Sect refined qi, but it refined blood. After the initial stage of Skinning Cultivation, its practitioner could gather, disperse, and transform, gaining a measure of the divine ability possessed by Heavenly Immortals: "gathered, they took form; dispersed, they became primordial qi."
The Five Yin Demon General had only cultivated his primordial spirit into a life-bound god-demon, then used it to ascend here. This was equivalent to being reborn through reincarnation and obtaining the body of a deva.
The Lord of Stone God Palace, however, still retained the blood demon dharma body condensed from all the blood and vital energy of his original body. He could transform it at will, and the magical power he had accumulated over more than a thousand years in his previous life remained intact.
Simply put, other demons coming here underwent something like "rebirth" in Buddhism. Their lives in their original worlds ended, and they died. Amitabha guided their primordial spirits to the West, where they gained new life within lotuses. This was equivalent to passing through a tribulation of death: their time in the mortal world was their first life, and their time in the West was their second.
Buddhism taught that all phenomena arose from the mind. Those purple-gold bodies were condensed from the power of vows and cultivation within one's own mind and thoughts, not forged by tempering the flesh.