How were the living buddhas in Tibet selected? What are the procedures?

The reincarnation of living Buddha is a unique way of inheritance of Tibetan Buddhism. Since the reincarnation of the living Buddha was initiated by the Kagyu Sect of Tibetan Buddhism in the13rd century, other sects have followed suit. By the time New China was founded, there were thousands of reincarnation systems of living buddhas in various ethnic groups and regions that believed in Tibetan Buddhism, forming a huge group of living buddhas. Buddha is the abbreviation of the transliteration of Sanskrit Buddha. The original meaning of Sanskrit Buddha is "the awakened one" and "the knower". In the early days of Tibetan Buddhism, the person who succeeded in learning Buddhism and was able to guide others to realize the meaning of Buddhism was called a "guru" (Lama), and then he was regarded as a reincarnated Buddha who came to the world, thus creating the incarnation of seeking Buddha as the leader of religion and temple and the way of inheriting legal status. The so-called "incarnation Buddha" refers to a person who has made great achievements in studying Buddhism and practicing. After death, he can be reincarnated into another body according to his own wishes, return to the world, and continue to be universal. The theory of reincarnation of living Buddha is based on Buddhist teachings and theology, including the theory that Buddha has three bodies and the theory that the soul is immortal. "Three" means that there was a supreme Buddha as the master in the past, present and future; All beings are in the six divisions in the wheel of karma, which have no beginning and no end. Just like the rotation of the wheel, the incarnation of Buddha is no exception, but the Buddha is still a Buddha after reincarnation. This is the most basic part of Buddhist teachings, but there is no living Buddha and reincarnation of living Buddha in the belief practice of other Buddhist factions, which has become an important way to inherit the legal status of Tibetan Buddhism and one of the important characteristics that distinguish Tibetan Buddhism from other factions. The historical fact is that this way of inheritance was founded and formed after the formation of factions of Tibetan Buddhism in the post-macro period. At that time, there were contradictions and struggles among various sects to compete for believers, expand their influence and compete for spheres of influence. To this end, the reincarnated soul boy was put on the mysterious coat of the incarnation of Buddha and the immortality of soul, which was used to subdue people's hearts, eliminate criticism and strengthen his rule with divine power.