is an inscription written on a rock in the Bactrian language and the Greek script, which was found in 1993 at the site of
Rabatak, near
Surkh Kotal in
Afghanistan. The inscription relates to the rule of the
Kushan emperor
Kanishka, and gives remarkable clues on the genealogy of the Kushan dynasty. Bactrian became the
lingua franca of the Kushan Empire and the region of Bactria, replacing the Greek language. Bactrian was used by successive rulers in Bactria, until the arrival of the
Umayyad Caliphate.
Historical development Following the conquest of Bactria by
Alexander the Great in 323 BC, for about two centuries
Greek was the administrative language of his
Hellenistic successors, that is, the
Seleucid and the
Greco-Bactrian kingdoms. Eastern
Scythian tribes (the
Saka, or Sacaraucae of Greek sources) invaded the territory around 140 BC, and at some time after 124 BC, Bactria was overrun by a confederation of tribes belonging to the
Great Yuezhi and
Tokhari. In the 1st century AD, the Kushana, one of the Yuezhi tribes, founded the ruling dynasty of the
Kushan Empire. The Kushan Empire initially retained the
Greek language for administrative purposes but soon began to use Bactrian. The Bactrian
Rabatak inscription (discovered in 1993 and deciphered in 2000) records that the Kushan king
Kanishka () discarded Greek ("Ionian") as the language of administration and adopted Bactrian ("Arya language"). The Greek language accordingly vanished from official use and only Bactrian was later attested. The
Greek script, however, remained and was used to write Bactrian. The territorial expansion of the Kushans helped propagate Bactrian in other parts of
Central Asia and
South Western Asia. In the 3rd century, the Kushan territories west of the
Indus River fell to the
Sasanians, and Bactrian began to be influenced by
Middle Persian. The eastern extent of the Kushan Empire in Northwestern India, was conquered by the
Gupta Empire. Besides the
Pahlavi script and the
Brahmi script, some coinage of this period is still in the Aryo (Bactrian) script. From the mid-4th century, Bactria and northwestern India gradually fell under the control the
Hephthalite and other
Huna tribes. The Hephthalite period is marked by linguistic diversity; in addition to Bactrian, Middle Persian,
Indo-Aryan and
Latin vocabulary is also attested. The Hephthalites ruled these regions until the 7th century, when they were overrun by the
Umayyad Caliphate, after which official use of Bactrian ceased. Although Bactrian briefly survived in other usage, that also eventually ceased, and the latest known examples of the Bactrian script, found in the
Tochi Valley in Pakistan, date to the end of the 9th century. ==Writing system==