Kushan Empire

The Kushan Empire existed from around 30 to 375 CE. It was created by the Yuezhi people in the early first century CE. The empire began in the region of Bactria and grew to cover large parts of modern-day Afghanistan, India, Pakistan, Tajikistan, Turkmenistan, and Uzbekistan. In India, Kushan control reached at least as far as Saketa and Sarnath near Varanasi, where inscriptions from the time of Emperor Kanishka the Great have been found.

The Kushans were likely one of five tribes within the Yuezhi confederation. The Yuezhi were Indo-European nomads, possibly of Tocharian origin, who moved from northwestern China (Xinjiang and Gansu) and settled in ancient Bactria. The empire's founder, Kujula Kadphises, adopted Iranian and Greek cultural styles and imagery, following the Greco-Bactrian tradition. He was also a follower of the Shaivite sect of Hinduism, as were later Kushan kings Vima Kadphises and Vasudeva II. The Kushans were strong supporters of Buddhism, and starting with Kanishka, they also included elements of Zoroastrianism in their religious system. They helped spread Buddhism to Central Asia and China, and their rule brought about 200 years of relative peace, sometimes called the "Pax Kushana."

At first, the Kushans used Greek for official business, but soon switched to the Eastern Iranian language Bactrian. Kanishka sent his armies north of the Karakoram mountains. A direct route from Gandhara to China stayed under Kushan control for over a century, encouraging travel across the Karakoram and helping Mahayana Buddhism reach China. The Kushan dynasty had diplomatic ties with the Roman Empire, Sasanian Persia, the Aksumite Empire, and China's Han dynasty. The empire was a hub for trade between Rome and China. According to Alain Daniélou, it was for a time the central point of the major civilizations. Although much philosophy, art, and science developed within its borders, the only written records of its history come from inscriptions and accounts in other languages, especially Chinese.

The Kushan Empire broke into semi-independent kingdoms in the third century CE. These fell to the Sasanians invading from the west, who set up the Kushano-Sasanian Kingdom in Sogdiana, Bactria, and Gandhara. In the fourth century, the Gupta dynasty pressed from the east. The last Kushan and Kushano-Sasanian kingdoms were eventually overcome by northern invaders called the Kidarites, and later the Hephthalites.

Chinese sources name the Guishuang—the Kushans—as one of five noble tribes of the Yuezhi. Many scholars think the Yuezhi were Indo-European, with some suggesting a Tocharian origin, while others propose an Iranic Saka origin. The Yuezhi lived in the grasslands of eastern Xinjiang and northwestern Gansu in modern-day China until their king was killed by the Xiongnu, who were also fighting China. This forced the Yuezhi to migrate west between 176 and 160 BC. The five Yuezhi tribes were the Xiumi, Guishuang, Shuangmi, Xidun, and Dumi.

Around 135 BC, the Yuezhi reached the Hellenic kingdom of Greco-Bactria in northern Afghanistan and Uzbekistan. Pressured by the Yuezhi and the Scythians they displaced, the Greek dynasties moved southeast into the Hindu Kush and the Indus basin, where the Indo-Greek kingdoms were located. In South Asia, Kushan emperors regularly used the dynastic name "Koshano" on their coins. Several Sanskrit inscriptions in Brahmi script, such as the Mathura inscription of a statue of Vima Kadphises, refer to the Kushan emperor as "Kushana." Some later Indian texts called the Kushans Turushka, a name later confused with Turk, likely because Tukharistan came under western Turkish control in the seventh century. According to John M. Rosenfield, Turushka, Tukhara, or Tukhāra are variations of the word Tokhari in Indian writings. André Wink states that no historian today considers them Turkish-Mongoloid or Hun, though their Central Asian origin is certain. A 2013 genetic study of burial sites identified as Yuezhi compared with those of Tocharians suggested they were different peoples. The authors found that Tocharian paternal lineages were from East Eurasians, unlike the Yuezhi, and thus they did not share the same origin. The study proposed the Yuezhi were a unique Central Asian group with West Eurasian origin, but noted more evidence was needed to clarify the Tocharian-Yuezhi relationship.

Traces of the Kushans in Bactria and Sogdiana exist from the second and first centuries BC, where they displaced the Sakas, who moved south. Archaeological sites include Takht-i Sangin, Surkh Kotal (a monumental temple), and the palace of Khalchayan. On the ruins of ancient Hellenistic cities like Ai-Khanoum, the Kushans built fortresses. Sculptures and friezes from this period show horse-riding archers and figures such as the Kushan prince of Khalchayan with artificially deformed skulls, a practice well attested.