Lao language
The majority of people in present-day Isan speak the Lao language known as Isan. Many Khmer speakers live in the southern half and substantial minorities of Katuic speakers (i.e., Kuy, Bru, and So) also exist. Most Isan people are both conversant and to some degree literate in Central Thai. Before the central government introduced the Thai alphabet and language in regional schools, the people of Isan wrote in the Lao alphabet, a very similar script that Thai adopted. Most people still speak the Isan language, a dialect of the Lao language, as their first language. A significant minority in the south also speak Northern Khmer.