The Kushans overthrew the Saka-Parthian princes and established an empire which became one of the world's greatest and most distinguished both from the point of view of territory as well as cultural and religious achievements. The Kushan ruler who Conquered Pakistan was Vima Kadphises who was succeeded in about 78 A.D. by Kanishka. The Kushan rule, however, did not completely eliminate the Sakas from Pakistan.  They had permanently settled down in these areas in large numbers and continued to be governed by their princes who merely extended allegiance to the Kushan kings.This is proved by the Sue Vihara inscription in the Bahawalpur Division which is dated in the regnal year of Kanishka 11(89 A.D.). Even the era said to have been founded by Kanishka in 78 A.D. was known as Saka Era. "There is evidence to show that they (Sakas) still governed their own states, no doubt as feudatories more or less nominal of the Kushans." (Cambridge History of India, Vol.1, edited by E.J. Rapson).

The Kushans, with their capital at Purushapura (Peshawar) had their dominions on both sides of the Hindu Kush i.e., extending up to and including parts of Turkistan in the north-west, embracing the whole of modern Afghanistan, and in the east the entire Pakistan and major portion of northern India. The greatest ruler of the dynasty, Kanishka, had adopted Buddhism and it was during his period that both Buddhist religion and Greek art reached their zenith which is known under the nomenclature of Gandhara Civilization. It was again during his regime and because of his efforts that Buddhism spread in Central Asia and China. This period is regarded as the most important in the history of Buddhism.

The budding and blossoming of Gandhara art was not a new phenomena in Pakistan's history as this land had given birth to several such brilliant civilizations since pre-historic times beginning with Indus Valley Civilizadon.  Judeiro Daro and Shahi Tump in Baluchistan; Moenjo Daro, Kot Diji, Amri, Chanhu Daro, and Sehwan in Sind; Harappa, Sari Kola and Taxila in the Punjab, Takht-i-Bahi and Mingora in NWFP have been seats of learning and art, centres of great religious activity and pivots of political power. It may be pointed out that Sari Kola in Pindi Division (3000 B.C.), Kot Diji in Khairpur Division (2800 B.C.) and Amri in Dadu District (3000 B.C.) are all pre-Indus Valley civilizations.

"When the great monarch Kanishka actively espoused the cause of Buddhism and essayed to play the part of a second Ashoka, the devotion of the adherents of the favoured creed received an impulse which speedily resulted in the copious production of artistic creations of no small merit.

"In literature the memory of Kanishka is associated with the names of the eminent Buddhist writers Nagarjuna, Asvaghosha and Vasumitra. Asvaghosha is described as having been a poet, musician, scholar, religious controversialist and zealous Buddhist monk. Charaka, the most celebrated of the early Indian authors treating of medical science, is reputed to have been the court physician of Kanishka.

"Architecture, with its subsidiary art of sculpture, enjoyed the liberal patronage of Kanishka, who was like Ashoka a great builder. The tower at Peshawar built over the relics of Buddha and chiefly constructed of timber stood 400 feet high. The Sirsukh section of Taxila hides the ruins of the city built by Kanishka. A town in Kashmir, still represented by a village bore the King's name." (Oxford History of India, by V.A. Smith).

A unique feature of Kanishka's empire was that with the capital at Peshawar its frontiers touched the borders of all the great civilizations of  the time, while its Central Asian provinces lay astride the Roman Middle East-Chinese trade routes. Roman Empire during the days of Trajan and Hadrian (98-138 A.D.) had expanded furthest East almost touching Pakistan's Kushan Empire. Similarly, Kanishka's conquests had brought Khotan,Yarkand and Kashgar within Pakistan's jurisdiction effecting direct contact with China. This was one of the most important factors in providing impetus to art and architecture, science and learning in Pakistan. The best specimen of Graeco-Roman art discovered in and around Peshawar, Swat and Taxila belong to this period, mostly executed during the 2nd century A.D. in the reigns of Kanishka and his son Huvishka. The Kushans exchanged embassies with the Chinese as well as the Romans. Mark Antony had sent ambassadors, and the Kushans sent a return embassy to the court of Augustus "In the middle of the first century of our era, one of the Tokhari princes belonging to the Kushans, Kujula Kadphises, unified the dispersed Tokhari principalities. As he grew stronger, the leader of the Kushans extended his suzerainship to the lands south of the Hindu Kush, in the Kabul Basin and on the Upper Indus. Kujula Kadphises's successors, the most prominent  of whom was Kanishka (circa A.D. 78-120) kept on the expansive policy of his subcontinent (Kashmir, the Punjab and Sind). The rulers of Gujrat, Rajasthan and the states lying in the Ganges-Jumna doab were the vassals of the Kushan kings. The Kushan kings also held control of the territory of the present day Afghanistan, Kashgar, Khotan, Yarkand and the southern areas of Middle Asia. Gandhara i.e., the territory lying in the valleys of the Kabul and the Middle Indus, became the centre of a vast empire.  The city of Purushapura (the present-day Peshawar) is known to have been the capital of Kanishka.

"The Kushan empire dissolved in the third century of our era. The Iranian shahs of the Sassanid dynasty took in the western territories. Various dynasties of Middle Asia took hold of the lands north of the Hindu Kush." (The Peoples of Pakistan, By Yu.V.Gankovsky).

After ruling for over two hundred years from the middle of the 1st century A.D.  to the middle of the 3rd century A.D. the Kushan Empire collapsed. Already, a few decades earlier, its frontiers had shrinked to those of Pakistan having shed the territories beyond Hindu Kush in Central Asia and eastward of Sutlej in India. The final blow was administered by Shahpur I, the head of a new dynasty of Sassanians that had emerged in Iran in 226 A.D. after a long period of anarchy prevailing for over 500 years since Alexander had eliminated the Achaemenians. "Shahpur I clearly includes in his Empire the greater part of Pakistan. Shahpur's son Narses had been made Shah of Seistan, Baluchistan and Sind and the seashore i.e., Pakistan and a bit more." (Pakistan in early Sassanian times, By M. Sprengling).

But this time Iran could not keep its sway over Pakistan for long. Though defeated, Kushans continued to rule over Pakistan for a considerably long period with the smaller kingdoms still retained by the redoubtable Sakas---both being Central Asian tribes. It seemed that ethnically and politically the Central Asian elements had become a permanent feature of Pakistan. Strong Kushan-Saka dynasties continued to exist in Kabul and Pakistan until another great event in the history of this area i.e., the Hun invasions in the 5th century A.D.-----some principalities survived even till the Arab conquest.

An important development had taken place in the neighbouring Country of India a little earlier which deserves our attention. Buddhism, which was on the decline from the 3rd century A.D. onward was overthrown by Hinduism reasserting its lost hegemony. This process culminated with the coming into power of the Guptas by the end of the 4th century A.D. A point of considerable significance to be noted here is that though the Gupta Empire is considered one of the most glorious in the annals of Hindu history  covering a vast area of this sub-continent, yet it could not bring Pakistan under its tutelage. During the Gupta period, Pakistan was in the hands of Kushan Shahis and Sassanians. Even during Samudragupta's triumphal career this region remained independent of India. "Samudragupta did not attempt to carry his arms across the Sutlej or to dispute the authority of the Kushan kings who continued to rule in and beyond the Indus basin...... Gupta Empire....the greatest in India since the days of Ashoka-extended in the north to the base of the mountains, but did not include Kashmir." (Oxford History of India).