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:
Hubbard is lecturing about communication problems. He gives an example of Earth beings who are out of touch with a space civilization called the Marcab Confederacy. (According to Hubbard, Earth is a prison planet for the Marcabians and we are all inmates.)
Hubbard follows bit of history with an example of Christians who are not getting answers from God, and take out their anger on the Catholic Church.
Dianetically, the optimum individual is called the Clear. [...] A Clear can be tested for any and all psychoses, neuroses, compulsions and repressions (all aberrations) and can be examined for any autogenetic (self-generated) diseases referred to as psychosomatic ills. These tests confirm the Clear to be entirely without such ills or aberrations. Additional tests of his intelligence indicate it to be high above the current norm. Observation of his activity demonstrates that he pursues existence with vigor and satisfaction.
— L. Ron Hubbard Dianetics: The Modern Science of Mental Health