The Tai-Kadai language family is a group of languages primarily spoken in Southeast Asia and southern China. It includes several major languages, such as Thai, Lao, and Zhuang. These languages share common linguistic features and are known for their tonal nature, meaning that the pitch used when pronouncing a word can change its meaning. The origins of the Tai-Kadai family are still debated among linguists, but it is believed to have emerged around 2,000 years ago. The languages are often classified into two main branches: Tai and Kadai. The Tai branch includes languages spoken in Thailand and Laos, while the Kadai branch is found in parts of southern China and Vietnam.