check this site:http://www.bvom.com/resource/vn_ethnic.asp?pContent=Features
scroll down and you'll see a list of ethnic minorities of vietnam. many of them are of mon-khmer origin. these people were probably part of a mass migration of
mon-khmer people who migrated to SEAsia thousands of years ago..
QUOTE
Child_.--So, _kon_; Suk, _kon_; Mon, _kon_; Hueei, _kuon_; Annan,
_kon_; Khmer, _kun_; Khasi, _khun_. Compare Nancowry, _kon_.
_Eye_.--The word _mat, mat, mat_, run through several of these
languages, e.g. Mon, _mat_; Huei, _mat_; Stieng; _mat_; Bahnar _mat_;
Annam, _mat_; Khasi, _khmat_ (dialectic _mat_). In Nancowry compare
_olmat_, eye, and _okmat_, eyebrow, and (_e_)_mat_ (_hen_) _mat_
(_drug_), _mat_, of the Nicobar dialects, also Semang _mat, met,
med_. Kuhn remarks that the word _mat_ is common for "_sight_," and
"eye" all over the Malay Archipelago. It should be remarked that in
the Amwi and Lakadong dialects of Khasi the word is _mat_.
_Nose_.--If we cut off the aspirate _kh_ from the Khasi _khmut_, which
thus becomes _mut_, we find some correspondence between Mon, _muh_
(_mu_); Stieng (_tro_), _muh_; Bahnar, _muh_. Here also compare Ho
_mua, muta_; Mundari, _mun_; Uraon, _moy_. In the Anwi and Lakadong
dialects of Khasi the word is _mur-kong_.
_Hand_.--Xong, _ti_; Mon, _toi_; Annam, _tay_, Khmer, _te_ (from
_sang te_, finger); Palaung, _tae, tai_, and Khasi, _kti_ (with
prefix _k_) closely correspond. The forms _ta_ and _toi_ of Amwi,
and Lakadong, respectively, still more closely correspond with the
Mon-Khmer languages than with Khasi. Here compare Nancowry _tei_
and _ti_, or _ti_ of the Kol languages.
_Blood_.--Palaung _hnam_, and Wa _nam_ closely correspond with Khasi
_snam_; here compare Khmer _iham_.
_Horn_:--Mon, _grang_, the horn of an animal, may be compared with
the Khasi _reng_.
_Far_.--Distant. Bahnar, _hangai_; Annam, _ngai_; Khmer, _chhngay_;
Lemet, _sngay_; Sue _chngai_ may be compared with the Khasi
_jing-ngai_. Amwi _shnjngoi_ seems to be a closer form to the above
than Khasi _jing-ngai_. But compare Mynnar (Jirang), _chngi_, which
is clearly very close to Sue _chngai_, and Khmer _chhngay_.
_To weep, to cry_.--Mon, _yam_; Khmer, _yam_; Khmu Lemet and Palaung,
_yam_, are clearly the same as Khasi _iam_, with which also may be
compared Ho _yam_.
some of the words are exactly identical. such as the word for "weep". mon=yam,khmer=yam,palaung=yam,khasi=iam