A struggle for power began with Bimbsara and Ajatsatru of the kingdom of Magadh. In the 4 Century BC, the Nandas came to power, with their capital at Patliputra. The latter were replaced by Mauryas at the close of same century. This came about partly as a result of Alexander ’s invasion and decline of Iranian strength in India. Chandra Gupta Maurya took advantage of unsettled conditions and with the help of advisor Kautilya, built the first great empire of India. Under him and his two great successors Bindusar and Ashoka, almost the whole of India with the exception of farthest south, was unified into one empire.

Many important developments took place in the social, economic and cultural life of the Indian people in this period. Particularly important was the spread of Buddhism, which had been introduced earlier.

The decline of the Mauryan empire after the rule of Ashoka was followed by a long period of new invasions and the formation of small states. Of the foreign invasions, the first was that of the Greeks who were the rulers of Bactria. They conquered the Punjab and part of Sind and their contact had a lasting influence on the culture of India. Gandhara style of art emerged and flourished. The greatest Greek ruler in India was Menander in 2 century BC who became Buddhist. The Greek invasion was followed by Sakas. The saka displaced the Greek in Bactria and spread their power in western India. One of the Saka kind was Rudradaman who as name suggests, was a devotee of Shiva. He was responsible for important irrigation works in Saurastra. The Sakas, like other invaders, became a part of Indian life and played an important role in the development of Indian culture.

Another group of Invaders in central India was that of the Kushans. The Greatest of Kushan ruler was Kanishka who according to some historians started Saka era. Kanishka ruled his vast empire in India and central Asia from Puruspura for 40 years. Kaniska ’ s Empire brought to India the cultural tradition of Iran, Greece and Rome. It also provided a stimulus to trade between India and other parts of the World. Kanishkra patronized the Mahayana form of Buddhism. It spread to central Asia during this period and from there to China, Korea and Japan. The Kushana Empire declined in the third century.