Thai is a tonal monosyllabic language. The same word can be said in five different ways - normal or middle tone, high, low, rising and falling. In Thai the meaning of single syllable may be alter in five different tones.
Thai is one of the oldest languages in East and South-East Asia. According to linguist, it may event pre-date Chinese, at least in its prototypical form. Many of the so-called "loan-words" thought to be borrowed from Chinese by the Thais actually have an Austro-Thai origin. At any rate, Chinese and Thai have many similarities, since both are monosyllabic tonal languages.