I recall participating in a discussion on the topic of loanwords. Specifically, musing on the vast number of English loans in Thai, and wondering if there could possibly be any Thai loans in English. My immediate reaction was that there wouldn't be, because native English speakers don't have sufficient exposure to the Thai language in any statistically significant way. Then someone suggested pad thai, I think it was. Which is a good point. Thai food is immensely popular in the U.S., at least, and we have two choices for how to deal with the abundance of varieties of Thai (or any foreign) cuisine: (1) give it a descriptive English name, or (2) use its native name.
On your average Chinese menu, for example, you'll see both "beef with broccoli" and "moo goo gai pan." We could call the latter "mushroom chicken," but we don't (or at least, most places I've been to don't).
We borrow the names for lots of foreign dishes: from French, we have filet mignon, and escargot; from Italian, everything from spaghetti to cacciatore; from Spanish, paella; from Arabic, couscous.
And from Thai, we have examples of both naming options in papaya salad (for ส้มตำ), a descriptive name, and mee krob (หมี่กรอบ) or pad thai (ผัดไทย), native names. Of course, there is variation from restaurant to restaurant, but many dishes are best known by their Thai names.
Borrowing words is a natural social and linguistic process. And learning new concepts from foreign cultures is a very common (and totally legit) reason to introduce loanwords into another language (although some countries feel that they have to come up with more native-sounding alternatives). Something like pad thai has no English name at first. Whether we will all end up calling it, say, Thai spaghetti (which I sometimes have done) or just adopt the native name (which already conveniently has the word thai in it anyway) is something that can't be predicted. Whatever sticks. And it appears, in several cases, that English has adopted a few words from Thai. Who'da thunk it.