cities in the region. Early Buddhist sources report a city being built in the vicinity of the village towards the end of the Buddha's life; this generally agrees with archaeological evidence showing urban development occurring in the area no earlier than the 3rd or 4th Century BCE. In 303 BCE, Greek historian and ambassador Megasthenes mentioned Pataliputra as a city in his work Indika.Diodorus, quoting Iambulus mention that the king of Pataliputra had a " great love for the Greeks ". The city of Pataliputra was formed by fortification of a village by Haryanka ruler Ajatashatru, son of Bimbisara. Its central location in north eastern India led rulers of successive dynasties to base their administrative capital here, from the Nandas, Mauryans, Shungas and the Guptas down to the Palas. Situated at the confluence of the Ganges, Gandhaka and Son rivers, Pataliputra formed a "water fort, or jaldurga". Its position helped it dominate the riverine trade of the Indo-Gangetic plains during Magadha's early imperial period. It was a great centre of trade and commerce and attracted merchants and intellectuals, such as the famed Chanakya, from all over India. Two important early Buddhist councils are recorded in early Buddhist texts as being held here, the second session of the Second Buddhist council in the reign of Ashoka, 35 years after the first session held in Vaisali and the Third Buddhist council. Jain and Brahmanical sources identify Udayabhadra, son of Ajatashatru, as the king who first established Pataliputra as the capital of Magadha. The Sangam Tamil epic Akanaṉūṟu mentions Nanda kings ruling Pataliputra. Capital of the Maurya Empire During the reign of Emperor Ashoka in the 3rd century BCE, it was one of the world's largest cities, with a population of about 150,000–400,000. The city is estimated to have had a surface of 25.5 square kilometers, and a circumference of 33.8 kilometers, and was in the shape of a parallelogram and had 64 gates (that is, approximately one gate every 500 meters). Pataliputra reached the pinnacle of prosperity when it was the capital of the great Mauryan Emperors, Chandragupta Maurya and Ashoka. The city prospered under the Mauryas and a Greek ambassador, Megasthenes, resided there and left a detailed account of its splendour, referring to it as "Palibothra": Strabo in his Geographia adds that the city walls were made of wood. These are thought to be the wooden palisades identified during the excavation