Huỳnh Phú Sổ was born on 15 January 1920 in the village of Hòa Hảo, near Châu Đốc, to a family of modest landholders. Illness took hold of him at fifteen and did not let go. He had no formal education and no contact with Saigon's Westernised intelligentsia; what he had was the Bảy Núi range sixty kilometres away, a landscape of isolated peaks full of hermits and healers, where he absorbed an unorthodox composite of Buddhist teaching. He came back apparently cured and began to preach. His followers date the founding to the eighteenth day of the fifth lunar month of kỷ mão - mid-1939. He declared himself a prophet, travelled the delta practising herbal medicine and acupuncture on patients who said he cured what French medicine could not, and gave away his teachings as cheap verse pamphlets. He also predicted a great war in the Far East and the expulsion of Europeans by Asians, an eccentric thing to say in 1939 and an obvious truth by 1942. Ten thousand followers in that first year became a hundred thousand by 1940 and near a million by late 1944.

The doctrine reworked an older regional tradition, Bửu Sơn Kỳ Hương, traced to the nineteenth-century master Phật Thầy Tây An. It is Buddhist at its core, blended with ancestor veneration, animist practice and Confucian ethics, and shaped for peasants. There is no monastic order to support, no elaborate ritual, no expensive statuary. Prayer happens four times daily at home, and a believer who has lived correctly needs only a simple funeral. Sổ preached against the sale of child brides, against gambling, alcohol and opium, and against usury; he distrusted cities as places of competition and display that dissolve communal obligation. Underneath sits a millenarian clock borrowed in part from the Chinese White Lotus tradition: three great eras, the present one grinding toward catastrophe, then the Assembly of the Dragon Flower, where Maitreya presides over a world morally remade. Outsiders called it the poor man's Buddhism. It was meant to be.

Colonial authorities read this as sedition waiting to happen. In 1940 the Vichy governor Jean Decoux had Sổ committed as a lunatic at Bạc Liêu, where he converted his own psychiatrist; French doctors declared him sane in 1941 and he was exiled anyway; Bạc Liêu promptly became a pilgrimage site. By 1942 the French shipped him to Laos, and the Japanese, who understood exactly what they had, intercepted him and installed him in Saigon under military protection. The first Hòa Hảo militias appeared in late 1943 as village self-defence units and hardened fast into something else. When Japan surrendered, the delta became a four-way fight, and in September 1945 fifteen thousand Hoahaoists armed with hand weapons attacked the Việt Minh garrison at Cần Thơ and were slaughtered. The reprisals were as ugly as the massacre that provoked them. Communist cadres were bound together and drowned in the canals; corpses were left in public, and villagers who flinched at the sight were marked as sympathisers.

In April 1947 the Việt Minh invited Sổ to a reconciliation meeting in the Plain of Reeds. He refused their terms and started home, was stopped on the river near Long Xuyên, and killed. He was twenty-seven. Knowing that a grave would become a shrine and a shrine a rallying point, his killers quartered his body and scattered the pieces; the remains were never recovered. Vietnamese police records later placed the death in December that year, complete with a trial - a fabrication, the historian Shawn McHale argues, invented to make a murder look like justice. A leader who simply vanished cannot be confirmed dead, and Hoahaoists mark the twenty-fifth day of the second lunar month not as his death but as his disappearance. His followers split into rival armed factions and fought the Communists for another three decades.

After 1975 the movement was dissolved, its leaders imprisoned, Sổ's writings banned and public reference to him forbidden, though private worship at the household altar was tolerated. Official recognition came only in 1999, and half a million believers gathered in An Giang that July. It was partial recognition: the state sanctions one branch, and the unregistered ones live under surveillance, checkpoints on festival days, bans on public readings of Sổ's texts, and arrests. Government figures count 1.3 million adherents; other estimates run to several million, concentrated almost entirely around Chợ Mới, Phú Tân, Châu Đốc and Long Xuyên. The largest community abroad is in Santa Ana, California, where the altars stand in front yards too.