Five things that define the Lui Chew

A homeland
The Leizhou Peninsula — the southernmost tip of mainland China — facing Hainan across the narrow Qiongzhou Strait, today within Zhanjiang, Guangdong.
A language
Leizhou Min (雷州话 / 黎话), ISO code luh — a branch of Min Chinese, classed as endangered.
A Min ancestry
Descended from Min migrants out of Fujian (especially Putian) who fled south in the late Song — a Min island inside Cantonese Guangdong.
A folk-culture
Thunder-Ancestor (雷祖) worship, the stone-dog (石狗) guardian cult, the Nianli (年例) festival, Leizhou song and Lei opera — several now national heritage.
Kin, not clones
Closely related to the Hainanese (the Qiong-Lei branch of Min) — but a distinct people with a distinct, mutually-unintelligible tongue.

A small people, a long memory, three nodes on the Strait.

The name: Lui Chew, Leizhou, Lei Zhou

If you have seen the name written several ways, that is normal. Lui Chew and Luichew are the older romanisations used in British Malaya and Singapore, and they are still the form the clan associations use — Persatuan Lui Chew Johor, the Lui Chiu Hoe Kuan in Singapore. Leizhou is the modern Hanyu Pinyin spelling; Lei Zhou is the same word spaced out. All of them are 雷州.

The place itself was named in the Tang dynasty: in 634 CE the founding prefect Chen Wenyu renamed the prefecture 雷州 — “thunder prefecture” — after a local thunder mountain and river. The people, the language and the diaspora all take their name from that thunder coast.

The language: Leizhou Min

Leizhou Min (雷州话, locally 黎话) is a branch of Min Chinese — the same broad family as Hokkien and Hainanese, but its own distinct language. Linguists place it with Hainanese in a “Qiong-Lei” (琼雷) group; the two are kin but not mutually understood. It keeps eight tones and the old -p / -t / -k final consonants of Middle Chinese — a conservative, Tang-era sound system that Mandarin has long since lost.

A living archive. In the few thousand who still speak it overseas, the word for "cow" is pronounced with a soft [ɓ] sound that has vanished from the mainland Leizhou homeland — meaning the Malaysian dialect is, in this respect, older than the one spoken in China today.

Overseas, Leizhou Min is “extremely endangered.” It is taught in no school, and younger generations have shifted to Mandarin and English. What contact it has had has been mostly with other Chinese tongues — Mandarin and Cantonese — rather than with Malay.

Lui Chew or Hainanese? Which am I?

This is the single most common confusion, and an understandable one. The Lui Chew and the Hainanese are the closest of kin: the same Qiong-Lei branch of Min, the same corner of the South China Sea, the same migration south, arriving in Malaya within a generation of each other. Many small Lui Chew communities elsewhere in Southeast Asia were simply absorbed into the larger Hainanese clan networks. But they are two peoples, not one — and here is how they differ.

Lui Chew (雷州) compared with Hainanese (海南)
Lui Chew (雷州)Hainanese (海南)
HomelandLeizhou Peninsula (mainland)Hainan Island
LanguageLeizhou MinHainanese Min
Mutually understood?No — same Qiong-Lei branch, but not mutually intelligible.
Earliest Melaka body18991869 (30 years earlier)
Niche in MalayaService trades, no signature dishCoffee shops, cooks — "Hainanese chicken rice"
Clan-house deitiesGuandi, Guanyin, Bai Ma Lao ShiMazu, the 108 Brothers
Size in Malaysia"A few thousand" speakers~141,000 (2001 census)

In one line: the Lui Chew are the Hainanese's smaller, later-arriving cousin — with a stone dog instead of a chicken-rice.

How close, exactly? About as close as Spanish and Italian. A speaker of one can pick out individual words of the other but cannot hold a conversation — the two are not mutually intelligible. A Lui Chew speaker actually has slightly better odds understanding Hokkien than Hainanese.

Where the linguists disagree. Even the grouping is debated. Hou Jingyi places Leizhou Min and Hainanese together as one "Qiong-Lei" (琼雷) branch; Yuan Jiahua files Leizhou under Southern Min, with Hokkien and Teochew; Li Rong treats it as its own Min sub-branch. The Qiong-Lei pairing is a minority view — but the strongest single statement of kinship is plain: the consonant systems of the two correspond closely.
Hear it yourself. For the Leizhou sound, the modern dialect anthem 《我是雷州人》 ("I am a Leizhou person"); for Hainanese, any Hainan-opera (琼剧) clip. They share a rhythm and a consonant inventory, but differ in tone and vocabulary — a kinship you can hear without understanding.

The kinship runs deeper still: both peoples reach back to a far older shared past — see Deep Ancestry.

How many Lui Chew are there?

It depends on what you count, so we keep two numbers apart. In China, there were about 2.8 million Leizhou Min speakers as of a 2004 estimate, with the broader Leizhou sub-group of the Zhanjiang region put at around 4.5 million. In Malaysia, the living dialect community is only “a few thousand … extremely endangered.”

A figure to handle with care. One Chinese-encyclopaedia entry claims more than 1.5 million people of Leizhou ancestral origin across Malaysia and Singapore. That figure uses a very broad ancestral definition, rests on a single source, and is far larger than the living dialect community — so we mention it but do not headline it. The honest picture: a possibly sizeable ancestry, but a very small living community.
What we don't know yet. The gap between "1.5 million ancestry" and "a few thousand dialect speakers" has never been closed by any independent study — no public census breaks out Leizhou Min as a separate category. We do not know whether informal Lui Chew social circles exist in Malaysian towns outside Melaka and Muar that simply left no formal record. And no study has mapped how many Malaysian-born descendants still identify as Lui Chew without speaking the dialect. If your family carries a Lui Chew identity not captured in any record here, a contribution is welcome.