Vietnamese

Vietnamese language is part of the Austro-asiatic language family. It's the most spoken language of the family. Others related languages are Khmer (spoken in Cambodia) and a few minor languages spoken in Southwest Asia.
It was heavily influenced by Chinese - a lot of words is taken from it and also till the beginning of the 20th century Chinese signs were the predominant script, though now Vietnamese is written in Latin.
Also Vietnamese is a tonal language even though other Austro-asiatic languages are not - again the influence of Chinese or perhaps Thai.