according to carbon dating, were discovered in Singhbhum district. During the late Vedic period, several janapadas emerged in India. In the 6th century BCE, the mahajanapadas emerged in several parts of the Indian subcontinent. The region was the historical centre of the Nanda, Maurya, Shunga, Gupta and Pala empires that ruled much of the Indian sub-continent at their prime. In medieval India, it was incorporated into the Mughal, Maratha and then the British empire. After independence in 1947, the states joined the Indian Union and took their current form after the States Reorganisation Act of 1956. Today, they continue to face problems of overpopulation, environmental degradation and pervasive corruption despite significant economic and social progress. After the Kalinga War the Maurya king Ashoka sent emissaries to spread Buddhism across Asia. The university of Nalanda was in Bihar. Chinese travellers visited Buddhist and Hindu temples and libraries in the universities of Magadha Empire. The Emperor of Kalinga Mahameghavahana Aira Kharavela was one of the most powerful monarchs of ancient India. The Jain thirkhankar Mahaveer was born here and founded Jainism. Islamic invasions in the 13th century resulted in the collapse of Hindu kings and most Buddhists, especially in East Bengal, converted to Islam. East India including Bihar and West Bengal was part of the Mughal Empire in the 16th and 17th centuries. Odisha remained a powerful Hindu dynasty under the rule of Soma/Keshari Dynasty, Eastern Ganga Dynasty, Surya Dynasty till the end of the 16th century. The mighty Nalanda University existed at Nalanda which was destroyed by Bakhtiar Khilji during the 12th century and also defeated Sena Dynasty. Sher Shah Suri, who became king of India after defeating Humayun, founded the city of Patna on the ruins of ancient Pataliputra. Islam arrived during the 7th century CE and became dominant gradually since the early 13th century with the advent of Muslim rulers as well as Sunni missionaries such as Shah Jalal in the region. Later, Muslim rulers, starting from the Delhi Sultanate initiated the preaching of Islam by building mosques. From the 14th century onward, it was ruled by the Bengal Sultanate, founded by king Shamsuddin Ilyas Shah, beginning a period of the country's economic prosperity and military dominance over the regional empires, which was referred by the Europeans to as the richest country to trade with. Afterwards, the entire East India came under the Mughal Empire, becoming as the most