According to the introduction in the 2000 edition, “L. Ron Hubbard wrote Hymn of Asia for a Buddhist convention during the 1955-56 worldwide celebrations of the 2,500th year of the Buddhist era.” The specific prophesy he claimed to fulfill:

When he shall be seen in the West, seated in the Western fashion, his hair like flames about his noble head, discoursing, then shall the inhabitants of the Three Worlds (*) rejoice, knowing that the emancipation of all sentient beings is imminent. Then it shall be called the age of the blessed because it will become commonplace to achieve emancipation in one lifetime.” (*) The “Three Worlds” in Tibetan scripture refers to: Body (the physical world pertaining to the body and life), Speech (the “world” of communication between entities and things) and Mind (one’s own world, the world of one’s own Creation.)
—Hymn of Asia © 1974, 2000 L. Ron Hubbard Library