According to some sources, Orkhon script is derived from variants of the Aramaic alphabet, in particular via the Pahlavi and Sogdian alphabets of Persia, or possibly via Kharosthi used to write Sanskrit. Vilhelm Thomsen connected the script to the reports of Chinese account from a 2nd-century BCE Yan renegade and dignitary named Zhonghang Yue. Yue "taught the Chanyu to write official letters to the Chinese court on a wooden tablet 31 cm long, and to use a seal and large-sized folder". The same sources tell that when the Xiongnu noted down something or transmitted a message, they made cuts on a piece of wood. They also mention a "Hu script". At the Noin-Ula burial site and other Hun burial sites in Mongolia and regions north of Lake Baikal, the artifacts displayed over twenty carved characters. Most of these characters are either identical with or very similar to the letters of the Turkic Orkhon script. Turkic inscriptions dating from earlier than the Orkhon inscriptions used about 150 symbols, which may suggest that tamgas first imitated Chinese script and then gradually was refined into an alphabet. Contemporary Chinese sources conflict as to whether the Turks had a written language by the 6th century. The Book of Zhou, dating to the 7th century, mentions that the Turks had a written language similar to that of the Sogdians. Two other sources, the Book of Sui and the History of the Northern Dynasties claim that the Turks did not have a written language. According to István Vásáry, Old Turkic script was invented under the rule of the first khagans and that it was modelled after the Sogdian fashion. Several variants of the script came into being as early as the first half of the 6th century.
Corpus
The Old Turkic corpus consists of about two hundred inscriptions, plus a number of manuscripts. The inscriptions, dating from the 7th to 10th century, were discovered in present-day Mongolia, in the upper Yenisey basin of central-south Siberia, and in smaller numbers, in the Altay mountains and Xinjiang. The texts are mostly epitaphs, but there are also graffiti and a handful of short inscriptions found on archaeological artifacts, including a number of bronze mirrors. The website of the lists 54 inscriptions from the Orkhon area, 106 from the Yenisei area, 15 from the Talas area, and 78 from the Altai area. The most famous of the inscriptions are the two monuments which were erected in the Orkhon Valley between 732 and 735 in honor of the Göktürk prince Kül Tigin and his brother the emperor Bilge Kağan. The Tonyukuk inscription, a monument situated somewhat farther east, is slightly earlier, dating to ca. 722. These inscriptions relate in epic language the legendary origins of the Turks, the golden age of their history, their subjugation by the Chinese, and their liberation by Bilge. The Old Turkic manuscripts, of which there are none earlier than the 9th century, were found in present-day Xinjiang and represent Old Uyghur, a different Turkic dialect from the one represented in the Old Turkic inscriptions in the Orkhon valley and elsewhere. They include Irk Bitig, a 9th-century manuscript book on divination.
Table of characters
Old Turkic being a synharmonic language, a number of consonant signs are divided into two "synharmonic sets", one for front vowels and the other for back vowels. Such vowels can be taken as intrinsic to the consonant sign, giving the Old Turkic alphabet an aspect of an abugida script. In these cases, it is customary to use superscript numerals ¹ and ² to mark consonant signs used with back and front vowels, respectively. This convention was introduced by Thomsen, and followed by Gabain, Malov and Tekin.
Vowels
Consonants
;Synharmonic sets ;Other consonantal signs A colon-like symbol is sometimes used as a word separator. In some cases a ring is used instead. A reading example : transliterated t²ñr²i, this spells the name of the Turkic sky god, Täñri.
Variants
Variants of the script were found from Mongolia and Xinjiang in the east to the Balkans in the west. The preserved inscriptions were dated to between the 8th and 10th centuries. These alphabets are divided into four groups by Kyzlasov
The Asiatic group is further divided into three related alphabets:
Orkhon alphabet, Göktürks, 8th to 10th centuries
Yenisei alphabet,
* Talas alphabet, a derivative of the Yenisei alphabet, Kangly or Karluks 8th to 10th centuries. Talas inscriptions include Terek-Say rock inscriptions found in the 1897, Koysary text, Bakaiyr gorge inscriptions, Kalbak-Tash 6 and 12 inscriptions, Talas alphabet has 29 identified letters.
The Eurasiatic group is further divided into five related alphabets:
South-Yenisei, used by the Göktürks 8th to 10th centuries.
Two especially similar alphabets: the Don alphabet, used by the Khazars, 8th to 10th centuries; and the Kuban alphabet, used by the Bulgars, 8th to 13th centuries. Inscriptions in both alphabets are found in the Pontic–Caspian steppe and on the banks of the Kama river.
A number of alphabets are incompletely collected due to the limitations of the extant inscriptions. Evidence in the study of the Turkic scripts includes Turkic-Chinese bilingual inscriptions, contemporaneous Turkic inscriptions in the Greek alphabet, literal translations into Slavic languages, and paper fragments with Turkic cursive writing from religion, Manichaeism, Buddhist, and legal subjects of the 8th to 10th centuries found in Xinjiang.
The Unicode block for Old Turkic is U+10C00-U+10C4F. It was added to the Unicode standard in October 2009, with the release of version 5.2. It includes separate "Orkhon" and "Yenisei" variants of individual characters. Since Windows 8 Unicode Old Turkic writing support was added in the Segoe font.