Hashim was born in Midsayap, Cotabato (now Pagalungan, Maguindanao) on July 7, 1939, to a religious family, one of seven siblings.
He also pursued a doctorate degree but was not able to finish writing his dissertation due to his decision to return to the Philippines to organize a Moro revolutionary movement.
[1] Hashim along with other militants including Nur Misuari founded the Moro National Liberation Front (MNLF) in the 1970s.
Hashim later left the group in the later part of the decade to form the Moro Islamic Liberation Front (MILF).
[2] Hashim died on July 13, 2003, while in one of the MILF's camps in Butig, Lanao del Sur, due to complications caused by a heart disease and acute ulcer.