Is there a similarity between Cantonese and Thai? I've noticed that some words such as the word for chicken is the same.
A huge population of Northern Thai consists of Chinese and most of these Chinese come from Southern China Guangdong Province from an area/ city called 潮州 (Chao zhou /teochew).
Even today, most of these modern Thai Chinese can speak some Teochew although they may not understand Mandarin.
Due to mixing of cultures, some words could have translated to Thai. Pronunciation may be closer to Teochew than Mandarin.
I believe one of their kings was of Chinese descent as well.
As for Cantonese and Hokkien dialects, I believe that the prolonged encountering between Southern Chinese and Tai speakers (Zhuang ,Thai, Lao etc.) made their phonetic repertoire more rich than the Mandarin dialect. Many words in Cantonese and Hokkien sound very much like Thai, for example Number 1 - 10 or the names of common objects such as chair (Gao Ee), table (Tou), guest (Khaek/khek).
Mandarin has fewer sounds because the Chinese writing system has no phonetic information. You cannot make new sound with it. Chinese language appears phonetically pure because loan words and names are “dubbed” with closest sounding Chinese characters. Chinese used to borrow many words and terminologies from Sanskrit through Buddhism. But its writing system does not allow any systematic orthography which is needed in order to incorporate new linguistic elements from an Indo-European language. Japanese has the same problem, and though it now have separate kana scripts, Japanese language still have very few sounds.
actually there ARE similarities (im thai-chinese and i speak both mandarin & thai + i do understand a bit cantonese too) While chinese is a sino-tibetan language and thai isnt theres still many words who are very similar to eachother , thai (in case of pronouncing is the most similar to chinese and besides that some words are also similar to hindi and a lot also to vietnamese , whenever i hear vietnamese i feel like im hearing a different type of thai) also both thai & chinese are tonal languages such as lao and viet. the comment with a past king was right (several thailand kings were actually chinese) + Thai people MIGRATED from SOUTH China 4000 years ago , so theres still a language in southern china thats very similar to the modern thai language. Thais originated from there and it stuck with them even though there were some changes since they moved south to the now land that first was called SIAM and now thailand. u can get the info about the thai volks origins in some HISTORY books about thailands people and where they actually came from. It was also mentioned in at least SOME documentations (history docu.) that thais originally came from south china (btw a lot of the south chinese ppl still look similar to thais) thats why some of the thai language has some similarities with chinese, even though cantonese is more similar to it instead of mandarin.