The Sassanids, shortly after victory over the Parthians, extended their
dominion into Bactria during the reign of Ardashir I around 230 CE, then
further to the eastern parts of their empire (modern Pakistan and India) during
the reign of his son Shapur I (240-270). Thus the Kushans lost their western
territory (including Bactria and Gandhara) to the rule of Sassanid nobles named
Kushanshahs or "Kings of the Kushans".
Kartir, a high-priest that served as advisor to at least three of the early
kings, instigated the persecution of non-Zoroastrians, that is, Christians,
Buddhists, Jews, Hindus and - in particular - the Manichaeans, who were
primarily in and from the eastern territories. The persecution ceased during
the reign of Narseh (r. 293–302).
Around 325, Shapur II was directly in charge of the southern part of the
territory, while in the north the Kushanshahs maintained their rule until the
rise of the Kidarites.
The decline of the Kushans and their defeat by the Sassanids led to the rise
of an indigenous Indian dynasty, the Guptas, in the fourth century. In 410 the Hephthalites
or Indo-Hephthalites conquered Bactria and Gandhara, thus temporarily replacing
the Indo-Sassanids.
The Hephthalites dominated the area until they were defeated
in 565 AD by an alliance between the Gokturks and Sassanids, and some
Indo-Sassanid authority was re-established. The Kushano-Hephthalites were able
to set up a rival states in Kapisa, Bamiyan, and Kabul. The 2nd Indo-Sassanid
period ended with the collapse of Sassanids to the Rashidun Caliphate in the
mid 600s AD. Sind remained independent until the Arab invasions of India in the
early 8th century. The Kushano-Hephthalites or Turkshahis were replaced by the
Hindu Shahi in the mid 8th century.
The prophet Mani (210-276), founder of Manichaeism, followed the Sassanids'
expansion to the east, which exposed him to the thriving Buddhist culture of Gandhara.
He is said to have visited Bamiyan, where several religious painting are
attributed to him, and is believed to have lived and taught for some time. He
is also related to have sailed to the Indus valley area of India in 240 or 241,
and to have converted a Buddhist King, the Turan Shah of India.
On that occasion, various Buddhist influences seem to have permeated
Manichaeism: "Buddhist influences were significant in the formation of
Mani's religious thought. The transmigration of souls became a Manichaean
belief, and the quadripartite structure of the Manichaean community, divided
between male and female monks (the 'elect') and lay follower (the 'hearers')
who supported them, appears to be based on that of the Buddhist sangha"
(Richard Foltz, Religions of the Silk Road).