The unknown Kushan script (écriture inconnue in French, neizvestnoe pis’mo in Russian, both meaning unknown lettering[1]) is a partially deciphered writing system and abugida, written from right to left, used to record a Middle Iranian language related to Bactrian.
It was used in parts of Central Asia between 600-200 BCE (depending on the age of the Issyk inscription) and 700 CE, including the Kushan Empire, associated with the nomads of the Eurasian Steppe in ancient Bactria.
[1] The partial decipherment was announced on 1 March 2023 by a team at the University of Cologne, when the consonant values of 15 signs, 2 ligatures, and 4 vowel diacritics had been determined.
A significant discovery that led to progress on decipherment was a bilingual carving found in the Almosi Gorge in northwestern Tajikistan, which included a section in the Bactrian language and ancient Greek writing.
[9] The Sakan hypothesis was also met with skepticism due to the possibility that the Issyk inscription originates from Bactria via trade or loot.