quality:corruption, linguistic:paraphrasing
The Kushan Empire (c. 30 – c. 375 AD) was a syncretic empire formed by the Yuezhi in the Bactrian territories in the early 1st century. It spread to encompass much of what is now Tajikistan, Uzbekistan, Afghanistan, Pakistan, Eastern Iran and Northern India, at least as far as Saketa and Sarnath, near Varanasi, where inscriptions have been found dating to the era of the Kushan emperor Kanishka the Great.

The Kushans were most probably one of five branches of the Yuezhi confederation, an Indo-European nomadic people of possible Tocharian origin, who migrated from northwestern China (Xinjiang and Gansu) and settled in ancient Bactria. The founder of the dynasty, Kujula Kadphises, followed Greek cultural ideas and iconography after the Greco-Bactrian tradition and was a follower of the Shaivite sect of Hinduism. Two later Kushan kings, Vima Kadphises and Vasudeva II, were also patrons of Hinduism. The Kushans in general were also great patrons of Buddhism, and, starting with Emperor Kanishka, they employed elements of Zoroastrianism in their pantheon. They played an important role in the spread of Buddhism to Central Asia and China, ushering in a period of relative peace for 200 years, sometimes described as " Pax Kushana ".

The Kushans possibly used the Greek language initially for administrative purposes but soon began to use the Bactrian language. Kanishka sent his armies north of the Karakoram mountains. A direct road from Gandhara to China remained under Kushan control for more than a century, encouraged travel across the Karakoram, and facilitated the spread of Mahayana Buddhism to China. The Kushan dynasty had diplomatic contacts with the Roman Empire, Sasanian Persia, the Aksumite Empire, and the Han dynasty of China. The Kushan Empire was at the center of trade relations between the Roman Empire and China: according to Alain Daniélou, "for a time, the Kushana Empire was the centerpoint of the major civilizations". While much philosophy, art, and science was created within its borders, the only textual record of the empire's history today comes from inscriptions and accounts in other languages, particularly Chinese.

The Kushan Empire fragmented into semi-independent kingdoms in the 3rd century AD, which fell to the Sasanians invading from the west and establishing the Kushano-Sasanian Kingdom in the areas of Sogdiana, Bactria, and Gandhara. In the 4th century, the Guptas, another Indian dynasty, also pressed from the east. The last of the Kushan and Kushano-Sasanian kingdoms were eventually overwhelmed by invaders from the north, known as the Kidarites, and later the Hephthalites.