A colophon to a Buddhist manuscript in Old Turkish from 800 AD states that it was translated from Sanskrit via a twγry language.
 In 1907, Emil Sieg and Friedrich W. K. Müller guessed that this referred to the newly discovered language of the Turpan area.

Sieg and Müller, reading this name as toxrï, connected it with the ethnonym Tócharoi (Ancient Greek: Τόχαροι, Ptolemy VI, 11, 6, 2nd century AD), itself taken from Indo-Iranian (cf.
Old Persian tuxāri-, Khotanese ttahvāra, and Sanskrit tukhāra), and proposed the name "Tocharian" (German Tocharisch).
 Ptolemy's Tócharoi are often associated by modern scholars with the Yuezhi of Chinese historical accounts, who founded the Kushan empire.
It is now clear that these people actually spoke Bactrian, an Eastern Iranian language, rather than the language of the Tarim manuscripts, so the term "Tocharian" is considered a misnomer.

Nevertheless, it remains the standard term for the language of the Tarim Basin manuscripts.

In 1938, Walter Henning found the term "four twγry" used in early 9th-century manuscripts in Sogdian, Middle Iranian and Uighur.
 He argued that it referred to the region on the northeast edge of the Tarim, including Agni and Karakhoja but not Kucha.
 He thus inferred that the colophon referred to the Agnean language.

Although the term twγry or toxrï appears to be the Old Turkic name for the Tocharians, it is not found in Tocharian texts.

The apparent self-designation ārśi appears in Tocharian A texts.
Tocharian B texts use the adjective kuśiññe, derived from kuśi or kuči, a name also known from Chinese and Turkic documents.
The historian Bernard Sergent compounded these names to coin an alternative term Arśi-Kuči for the family, recently revised to Agni-Kuči, but this name has not achieved widespread usage.
A colophon to a Buddhist manuscript in Old Turkish from 800 AD states that it was translated from Sanskrit via a twγry language.  In 1907, Emil Sieg and Friedrich W. K. Müller guessed that this referred to the newly discovered language of the Turpan area.
Sieg and Müller, reading this name as toxrï, connected it with the ethnonym Tócharoi (Ancient Greek: Τόχαροι, Ptolemy VI, 11, 6, 2nd century AD), itself taken from Indo-Iranian (cf. Old Persian tuxāri-, Khotanese ttahvāra, and Sanskrit tukhāra), and proposed the name "Tocharian" (German Tocharisch).  Ptolemy's Tócharoi are often associated by modern scholars with the Yuezhi of Chinese historical accounts, who founded the Kushan empire. It is now clear that these people actually spoke Bactrian, an Eastern Iranian language, rather than the language of the Tarim manuscripts, so the term "Tocharian" is considered a misnomer.
Nevertheless, it remains the standard term for the language of the Tarim Basin manuscripts.
In 1938, Walter Henning found the term "four twγry" used in early 9th-century manuscripts in Sogdian, Middle Iranian and Uighur.  He argued that it referred to the region on the northeast edge of the Tarim, including Agni and Karakhoja but not Kucha.  He thus inferred that the colophon referred to the Agnean language.
Although the term twγry or toxrï appears to be the Old Turkic name for the Tocharians, it is not found in Tocharian texts.
The apparent self-designation ārśi appears in Tocharian A texts. Tocharian B texts use the adjective kuśiññe, derived from kuśi or kuči, a name also known from Chinese and Turkic documents. The historian Bernard Sergent compounded these names to coin an alternative term Arśi-Kuči for the family, recently revised to Agni-Kuči, but this name has not achieved widespread usage.
Tocharian languages