It is unusual among early Cyrillic letters in having no direct counterpart in Glagolitic: Ⱑ (jat’) is used for both /ě/ and /ja/.

Nevertheless, Ꙗ is attested in the earliest extant Cyrillic writings, including for example the Codex Suprasliensis and Savvina Kniga - this was not supported to other fonts in other applications.

It continued in use in Serbian until the orthographical reforms of Vuk Karadžić, and in Bulgarian (where it also acquired a civil script glyph variant) until the late nineteenth century.

This is still the case in modern Church Slavonic, where, broadly speaking, Ꙗ is used initially and Ѧ elsewhere, though exceptionally they may be used to make other distinctions, such as that between ѧ҆зы́къ 'tongue' and ꙗ҆зы́къ 'people'.

[2] In cursive, the letter was modified: the left side was gradually lost, turning only into a flourish, so it began to look like an 'а' with a 'с'-shaped tail at the top left (a similar metamorphosis occurred with the cursive 'Ю').