The first Dalai Lama died in 1474 at 84. A year later, a young boy was seen as the first one's reincarnation, according to the movement's official website, "because of what he had to say about his amazing and flawless recollections of his past life."

http://www.sltrib.com/news/4019910-155/the-reborn-identity-dalai-lama-hints