How a language of seafarers ended up inland has a coastal answer. Jarai's closest relatives are Cham and Rade, the languages of Champa — the Cham polities that held the coast of what is now central and southern Vietnam for well over a thousand years. Champa was never purely Cham. Scholars describe it as polyethnic from the start, taking in Jarai and Rade speakers along with the Bahnaric- and Katuic-speaking peoples of the uplands, all of them in long and complicated contact with one another. The Chamic languages moved inland with the people who carried them, and once on the plateau they picked up the accent of the neighbourhood. Today the Jarai are the largest upland ethnic group in Vietnam's Central Highlands, and in Cambodia's Ratanakiri province they account for roughly a quarter of the indigenous population.

Centuries of living beside Mon–Khmer languages have reshaped Jarai from the inside. Chamic words across Southeast Asia have compressed into two syllables with the stress landing on the second, and Jarai travelled further down that road than most: the vowel of the unstressed first syllable has flattened almost out of existence, usually into a neutral schwa. Three-syllable words do exist, but every one of them is a loan. The inventory runs to twenty-four consonants and nine vowels, and the stressed vowel frequently opens into a diphthong. There is even a small border marker buried in the sound system — Jarai speakers in Cambodia use a voiced velar fricative that has never been recorded on the Vietnamese side. Pronouns, meanwhile, carry no gender at all.

Outside accounts of the Jarai have long fixated on the Pơtao: the Pơtao Apui, the Pơtao Ia, and the far less documented Pơtao Angin, rendered into French and English as the Kings of Fire, Water and Wind. The translation does most of the damage. They were not kings and governed no territory. They were ritual masters — custodians of ceremonies concerning rain and weather, associated in Jarai tradition with a sacred sword said to have come from heaven. Their standing reached well past their own villages; the Cambodian court sent offerings every three years, praying for peace and good seasons. The French arrived in the nineteenth century, the missionary Bouillevaux reporting on the Fire domain in 1850, and the relationship curdled: in 1904 the colonial official Prosper Odend'hal was killed by the Fire King. The last Pơtao Apui died in 1987. His intended successor, Siu Aluân, was never formally installed and died in 1999.

Jarai is written in a Latin-based alphabet fitted with characters built for it and its close relatives — a b with a stroke through it, ƀ, plus č and ñ pressed into service for sounds the plain letters could not hold. Vietnam recognises Jarai as an official minority language. Cambodia has no standard Khmer-script orthography for it. About 262,800 people speak the language, a figure well short of the number who identify as Jarai: Vietnam's 2019 census counted 513,930, Cambodia's 26,922. That gap is the ordinary arithmetic of a minority language under pressure. The dialects sit far apart from one another too, and speakers of the Pleiku, Cheoreo, ARáp, H'dRung and Tbuan varieties do not always understand each other. Several hundred speakers live in the United States, refugees of the war who carried the language across the Pacific — the family tree returning to the water by a very long detour.