Origin of the Brahui

[Psynome]

The Brahui people and their language have long posed a puzzle for scholars.

 The Brahui language is classified as a Dravidian language, yet the Brahui people are isolated from any other Dravidian speakers for hundreds of miles.

Some linguists have pointed out the Brahui language shares similarities Kurukh and Malto, two other isolated Dravidian languages. Yet genetic studies show the Brahui closely resemble their non-Dravidian speaking neighbors.

Did the Brahui originate in their current region, or did they migrate from somewhere else?

[szin]

I'm personally led to believe that some ancestors of the Brahui were Dravidians who moved northwest and mixed with the local population, who retained the Brahui language despite losing most of their Dravidian genetic affinity.

I have no idea why though.

[Psynome]

I'm personally led to believe that some ancestors of the Brahui were Dravidians who moved northwest and mixed with the local population, who retained the Brahui language despite losing most of their Dravidian genetic affinity.

I have no idea why though.

Yes, my further reading supports this. Linguistics provide the strongest argument; Brahui is most closely related to other Northern Dravidian languges like Kurukh and Malto. If Brahui was an old relict language of an original Dravidian homeland, it would likely be it's own highly diverged branch of Dravidian instead.

[pegasus]

The Brahui people and their language have long posed a puzzle for scholars.

 The Brahui language is classified as a Dravidian language, yet the Brahui people are isolated from any other Dravidian speakers for hundreds of miles.

Some linguists have pointed out the Brahui language shares similarities Kurukh and Malto, two other isolated Dravidian languages. Yet genetic studies show the Brahui closely resemble their non-Dravidian speaking neighbors.

Did the Brahui originate in their current region, or did they migrate from somewhere else?

There was a huge paper released on this, and it essentially pinpoints the origin of Dravidian languages to Balochistan.

Our putative Proto-Dravidian ancestry therefore evidently 265 constituted a separate entity that existed alongside the Iranian plateau farmer related ancestry since the 266 Neolithic period through the Chalcolithic in the vicinity of Indus Valley civilisation. The Elamo Dravidian theory and the linguistic phylogeny of the Dravidian family tree provide ideal chronological 268 fits for the genetic findings presented here.

https://www.biorxiv.org/content/10.1101/...1.587466v2

Novel 4,400-year-old ancestral component in a tribe speaking a Dravidian language

[kolompar]

Some authors deny that North Dravidian forms a valid subgroup, splitting it into Northeast (Kurukh–Malto) and Northwest (Brahui).[42] Their affiliation has been proposed based primarily on a small number of common phonetic developments, including:

    In some words, *k is retracted or spirantized, shifting to /x/ in Kurukh and Brahui, /q/ in Malto.
    In some words, *c is retracted to /k/.
    Word-initial *v develops to /b/. This development is, however, also found in several other Dravidian languages, including Kannada, Kodagu and Tulu.

McAlpin (2003) notes that no exact conditioning can be established for the first two changes, and proposes that distinct Proto-Dravidian *q and *kʲ should be reconstructed behind these correspondences, and that Brahui, Kurukh-Malto, and the rest of Dravidian may be three coordinate branches, possibly with Brahui being the earliest language to split off. A few morphological parallels between Brahui and Kurukh-Malto are also known, but according to McAlpin they are analyzable as shared archaisms rather than shared innovations.[43]

There's basically no difference between Brahui and their neighbors:

Code:

Distance to:    Brahui
0.00360450    Balochi_Pakistan
0.00786926    Balochi_Iran
0.00966371    Makrani
0.01163930    Sindhi_o
0.01451509    Balochi_Iran_o
0.02015273    Iranian_Bandari

Code:

Target: Brahui
Distance: 0.2505% / 0.00250494 | R5P
54.8    Balochi_Pakistan
22.4    Makrani
9.8    Sindhi_o
7.4    Balochi_Iran
5.6    Jat_Pahari

With the closest populations removed there's still nothing South Indian:

Code:

Target: Brahui
Distance: 2.2208% / 0.02220768 | R5P
39.0    Pashtun_Afghanistan
37.0    Rajput_Rajasthan
20.2    Iranian_Lor_Bakhtiari
3.8    Iranian_Mazandarani

Kurukh and Malto are Adivasi so it's both unlikely that they imposed their language with little gene flow and it would be easily detectable if they did. Indo-European languages are clearly dominant in the region and even today we largely see Brahui switch to their neighbors language and not the other way. I believe in the IVC origin of Dravidian and Brahui being the survivor there.

[parasar]

Kurukh and Malto are Adivasi so it's both unlikely that they imposed their language with little gene flow and it would be easily detectable if they did. Indo-European languages are clearly dominant in the region and even today we largely see Brahui switch to their neighbors language and not the other way. I believe in the IVC origin of Dravidian and Brahui being the survivor there.

I would think that Brahui arrived in region the middle Indo-Aryan period (~1000AD just pre-Baloch).  
Its oldest interaction in the region was with Jatki, then Balochi, then Persian/Arabic via Indo-Aryan and/or Balochi.  Brahui does not appear to have had any interaction with old-Indic or old-Persian, let alone Vedic or Gathic.  

"Brahui has been profoundly influenced by the languages of the neighbors among whom the tribesmen have been living, at the oldest level by Indo-Aryan (Sindhi-Siraiki “Jaṭki”). This early influence is most obvious in the Brahui lexicon but does not seem to have penetrated much deeper. The really deep influence on Brahui has been that of Baluchi, extending as it does not only to the Brahui lexicon but also to the phonology, many morphological aspects, and especially the syntax (see Emeneau, 1959; and especially Elfenbein, 1982, 1983). Thus Brahui phonology has been recast in a Baluchi mold. The aspectual system in the Brahui verbal system, both morphology and syntax, has been im­ported from Baluchi. Brahui has borrowed from Ba­luchi the nominal -ā case, some forms of kanning “do,” the -ok agent suffix, the syntax of the conjunction ki as well as the kind of parataxis usual in Baluchi, and the Baluchi group-inflection of nouns. Of the lexicon at a conservative estimate approximately 15 percent of Brahui is of native Dravidian origin, 20 percent is of Baluchi origin, 20 percent is of Indo-Aryan origin (including many “Jaṭki” words borrowed through Baluchi), 35 percent is of Persian/Arabic origin, mainly through Indo-Aryan or Baluchi; the remainder is of unknown origin."
https://www.iranicaonline.org/articles/brahui

"Dravidian covers all of the south and some parts of Central India as well as the North Dravidian outliers Brahui in Baluchistan, Kurukh in N. Madhya Pradesh, and Malto in S.E. Bihar. The latter three have moved out of Central India into their current homelands only around 1000 CE (Elfenbein 1987)."
https://www.ias.ac.in/article/fulltext/j.../0829-0833

[Andar]

Some authors deny that North Dravidian forms a valid subgroup, splitting it into Northeast (Kurukh–Malto) and Northwest (Brahui).[42] Their affiliation has been proposed based primarily on a small number of common phonetic developments, including:

    In some words, *k is retracted or spirantized, shifting to /x/ in Kurukh and Brahui, /q/ in Malto.
    In some words, *c is retracted to /k/.
    Word-initial *v develops to /b/. This development is, however, also found in several other Dravidian languages, including Kannada, Kodagu and Tulu.

McAlpin (2003) notes that no exact conditioning can be established for the first two changes, and proposes that distinct Proto-Dravidian *q and *kʲ should be reconstructed behind these correspondences, and that Brahui, Kurukh-Malto, and the rest of Dravidian may be three coordinate branches, possibly with Brahui being the earliest language to split off. A few morphological parallels between Brahui and Kurukh-Malto are also known, but according to McAlpin they are analyzable as shared archaisms rather than shared innovations.[43]

There's basically no difference between Brahui and their neighbors:

Code:

Distance to:    Brahui
0.00360450    Balochi_Pakistan
0.00786926    Balochi_Iran
0.00966371    Makrani
0.01163930    Sindhi_o
0.01451509    Balochi_Iran_o
0.02015273    Iranian_Bandari

Code:

Target: Brahui
Distance: 0.2505% / 0.00250494 | R5P
54.8    Balochi_Pakistan
22.4    Makrani
9.8    Sindhi_o
7.4    Balochi_Iran
5.6    Jat_Pahari

With the closest populations removed there's still nothing South Indian:

Code:

Target: Brahui
Distance: 2.2208% / 0.02220768 | R5P
39.0    Pashtun_Afghanistan
37.0    Rajput_Rajasthan
20.2    Iranian_Lor_Bakhtiari
3.8    Iranian_Mazandarani

Kurukh and Malto are Adivasi so it's both unlikely that they imposed their language with little gene flow and it would be easily detectable if they did. Indo-European languages are clearly dominant in the region and even today we largely see Brahui switch to their neighbors language and not the other way. I believe in the IVC origin of Dravidian and Brahui being the survivor there.

There is also no documentation of their migration (unlike for Balochs for example) from Central-North India and also not known Dravidian group between Brahui and North Dravidian that was documented. It looks pretty much like a local relict language and them clustering with Balochs doesnt mean much. Balochs came just in medieval era and Proto-Balochs from Iran would have been much more western shifted. It is easily possible that Dravidians in that region had extra Iran_N instead of extra AASI shift

[parasar]

I'm personally led to believe that some ancestors of the Brahui were Dravidians who moved northwest and mixed with the local population, who retained the Brahui language despite losing most of their Dravidian genetic affinity.

I have no idea why though.

Perhaps like the Oraon, Ho, Munda, Santhal, Asur, Kharia, Juang, etc.  The Oraon speak a Dravidian language, the rest Austroasiatic.
Genetically they are quite similar as they have been in close contact for about 1000 years.