Are Thai people partially South Asian?

[Sikeliot]

I am pretty sure I have read and seen in a study that Thai people are 15-20% South Asian in origins and have Indian-like ancestry. Is this true?

[Tooting Carmen]

All SE Asians have some overlap with Indians.

[Sikeliot]

All SE Asians have some overlap with Indians.

I think I saw that as far east as Cambodia have it, but Philippines and Vietnam do not.

[Iloko]

If I'm not mistaken I think Malaysians/Cambodians/Burmese have it the highest...around 22+% or so. Thais and Indonesians usually have it around 15-17%. Philippines around 4-7%. Vietnam much less.

I think it's normal for Malayans to have it, in fact Malays and tribal Cambodians/Thais are linked genetically through 'Austro-Asiatic/Proto-malay' ancestry. Proto-malayid and Proto-sinid also consumed some Indid when they migrated south to give rise to the 'Deutero-Malays':
https://scontent.fmnl3-2.fna.fbcdn.net/v/t31.0-8/26850248_10214562051339745_2435624637856241213_o.j pg?_nc_cat=0&oh=74e472eac9629b690dbad5bd85483439&oe=5BA239DA

I score 7%+ South Indian and 4% Oceanian on puntDNAL K15... though lukaszM says it's actually "Proto-Austronesian"---Viets and Mainland SE-Asians can harbor these components as well:
https://scontent.fmnl3-2.fna.fbcdn.net/v/t31.0-8/27624631_10214686154442245_1749484373469021734_o.j pg?_nc_cat=0&oh=2519ead54226bda7c8151b38f5e7ca2e&oe=5BA38C4A

Anyways I don't think SE-Asians necessarily need the South Asian admixture to look dark-skinned. Tropical adaptation and the Proto-malay influence can do it.