The Asshai'i language is spoken in the far east of Essos, in the city of Asshai. The faith of the deity R'hllor has notable ties to Asshai, and the name of the deity originates from the Asshai'i language. Loanwords from Asshai'i, such as that name, have entered into other languages of Essos, for example High Valyrian. The language is also used in the context of magic in the universe of A Song of Ice and Fire.
Out-of-universe, a sketch for the language was developed by David J. Peterson for use in Game of Thrones, however it was nearly absent from the aired episodes, and so the sketch as a whole is no longer considered canon. Individual loanwords in other languages have however been noted as coming from Asshai'i by Peterson, making the canonical existence of the developed language somewhat ambiguous as of the present moment (December 2021).