In terms of the datability of extant written sources, the period of Old Turkic can be dated from slightly before 720 AD to the Mongol invasions of the 13th century.

The only exceptions are 𐰤𐰀 (ne, "what, which") and its derivatives, and some early assimilations of word-initial /b/ to /m/ preceding a nasal in a word such as 𐰢𐰤 (men, "I").

[13] The script is named after the Orkhon Valley in Mongolia where early 8th-century inscriptions were discovered in an 1889 expedition by Nikolai Yadrintsev.

Variants of the script were found in Mongolia and Xinjiang in the east and the Balkans in the west.

However, Old Turkic also formed collective nouns (a category related to plurals) by a separate suffix -(A)gU(n) e.g. tayagunuŋuz ‘your colts’.

Today, all Modern Turkic languages (except for Chuvash) use exclusively the suffix of the -lAr type for plural.

This grammatical configuration is preserved in the majority of Modern Turkic languages, except for some such as Yellow Uyghur in which verbs no longer agree with the person of the subject.