[extract … ] The main archaeological sites of the Ganges plain were discovered by Alexander Cunningham, founder of Archaeological Survey of India. He covered the routes described by Faxian and Xuanzang, two Chinese pilgrims who visited India in the 5th and 7th century A.D., respectively. Cunningham identified and compared the mounds he visited with the cities described in the reports by the two pilgrims. In northern India only, he explored the sites of Mathura, Ahicchatra, Sankisa, Kanauj, Kausambi, Ayodhya, Sravasti, Kusinagara, Varanasi, Vaisali, Pataliputra, Bodhgaya, Rajagrha, Nalanda, Champa and Tamralipti.

The work of Cunningham was continued and extended by some of his successors at the Archaeological Survey of India and his discoveries were largely confirmed. Many sites identified by Cunningham have been explored during the last fifty years. Since then, stratigraphic excavations were utilized mainly to define different periods of occupation and to classify materials discovered into each layer1: in fact excavations were based on the method suggested byWheeler in two articles published in ancient India (1947 and 1947-48), a review that he founded with the aim to widen the knowledge of the ancient history of the subcontinent. In the first one, he supported the idea of a vertical stratigraphic excavation in order to clarify the cultural sequence of a site. In the second article, the proposal was to begin to work by excavating the fortification, considered as one of the more significant features in the history of a site.

It is from the Seventies that some studies (Ghosh 1973; Allchin, B. & R. 1982; Roy 1983, 1986; Erdosy 1987, 1988; Chakrabarti 1998) data coming from these excavations were taken into consideration to revise settlements dynamics and cultural development in the Ganges valley. Particular care was devoted to the Iron Age, when an urban civilization was born. In this context, the theory firstly asserted by Ghosh (1873: 66) that fortifications pertain to two different temporal phases gained consent. The first phase would go back to the 6th-5th century B.C. and the second to the last centuries of the 1stmillennium B.C.

• 1. Classes of objects like pottery, utensils, ornaments, coins, seals, terracotta figurines etc.