After the fall of Pagan, Mon again became the lingua franca of the Hanthawaddy Kingdom (1287–1539) in present-day Lower Myanmar, which remained a predominantly Mon-speaking region until the 1800s, by which point, the Burmese language had expanded its reach from its traditional heartland in Upper Burma into Lower Burma.

Following the fall of Pegu (now Bago), many Mon-speaking refugees fled and resettled in what is now modern-day Thailand.

[8] By 1830, an estimated 90% of the population in the Lower Burma self-identified as Burmese-speaking Bamars; huge swaths of former Mon-speaking areas, from the Irrawaddy Delta upriver, spanning Bassein (now Pathein) and Rangoon (now Yangon) to Tharrawaddy, Toungoo, Prome (now Pyay) and Henzada (now Hinthada), were now Burmese-speaking.

[9] The Mon language has influenced subtle grammatical differences between the varieties of Burmese spoken in Lower and Upper Burma.

[15] However, in this region, Burmese is favored in urban areas, such as Mawlamyine, the capital of Mon State.

[18][17] The remaining contingent of Thai Mon speakers are located in the provinces of Samut Sakhon, Samut Songkhram, Nakhon Pathom, as well the western provinces bordering Myanmar (Kanchanaburi, Phetchaburi, Prachuap Khiri Khan, and Ratchaburi).

[17] A small ethnic group in Thailand speak a language closely related to Mon, called Nyah Kur.

As in many Mon–Khmer languages, Mon uses a vowel-phonation or vowel-register system in which the quality of voice in pronouncing the vowel is phonemic.

There are two registers in Mon: One study involving speakers of a Mon dialect in Thailand found that in some syllabic environments, words with a breathy voice vowel are significantly lower in pitch than similar words with a clear vowel counterpart.

Some verbs have a morphological causative, which is most frequently a /pə-/ prefix (Pan Hla 1989:29): Mon nouns do not inflect for number.

That is, they do not have separate forms for singular and plural: sɔt pakawapplemo̤aoneme̤aCL{sɔt pakaw} mo̤a me̤aapple one CL'one apple'sɔt pakawapplebatwome̤aCL{sɔt pakaw} ba me̤aapple two CL'two apples'Adjectives follow the noun (Pan Hla p. 24): prɛ̤awomancebeautifulprɛ̤a cewoman beautiful'beautiful woman'Demonstratives follow the noun: ŋoadaynɔʔthisŋoa nɔʔday thisthis dayLike many other Southeast Asian languages, Mon has classifiers which are used when a noun appears with a numeral.

'ညးNyeh3တံtɔʔPLဗ္တောန်patonteachကဵုkɒtoအဲʔua1ဘာသာpʰɛ̤asalanguageအၚ်္ဂလိက်ʔengloitEnglishlistenⓘ  ညး တံ ဗ္တောန် ကဵု အဲ ဘာသာ အၚ်္ဂလိက်Nyeh tɔʔ paton kɒ ʔua pʰɛ̤asa ʔengloit3 PL teach to 1 language English'They taught me English.