The Kushans were a branch of the nomadic Yeuhchi tribe of China. The Yeuhchi tribe was in conflict with another tribe and so was forced to leave China. They came to Central Asia and then spread to Bactria, Paritha and Afghanistan. Gradually they were divided into five branches. One of these branches -- Kouel Chougang (Kushans) -- was superior to all. The Kushans under Kujala attacked the Parithans, took possessions of Ki-pin and Kabul and became the complete master of the Indian borderland.
Kujala became the first king of the Kushans and was known as Kadphises I. He was a great warrior. He was succeeded by his son Wima Kadphises known as Kadphises II. He conquered the north-western region of India. He defeated Saka Satraps in the north-west. Punjab and Sind were his dominions.
Kanishka was the most famous of the Kushan kings. It is not known how he became the king but he ascended the throne in AD 120. When Kanishka ascended the throne, his empire consisted of Afghanistan, Sind, Punjab and portions of the former Parithan and Bactrian kingdoms. His empire extended from the north-west and Kashmir, over most of the Gangetic valley. He annexed three provinces of the Chinese empire, namely, Tashkand, Khotan and Yarkhand. He was the only king who ruled over these territories. He had two capitals at Purushpura (Peshawar now in Pakistan) and at Mathura in west Uttar Pradesh. Kanishka proved that he was a great conqueror.
Kanishka`s immediate successor was Vashiska who was then succeeded by Huvishka. Mathura became the centre of Kushans. Many monuments were erected during Huvishka`s reign. The last great king of Kushans was Vasudev I. The Kushans were overthrown by the Sassanians of Persia in the north-west and the Guptas in the north. The rule of Kushans ended almost at the same time as that of the Satavahans in the south.