Stone age tools dating back 20,000 years have been excavated in the state. Remnants of civilization in the greater Bengal region date back four thousand years,when the region was settled by Dravidian, Tibeto-Burman, and Austro-Asiatic peoples. The exact origin of the word Bangla or Bengal is unknown, though it is believed to be derived from the Dravidian-speaking tribe Bang that settled in the area around the year 1000 BC. The region was a part of the Vanga Kingdom, one of ancient kingdoms of Epic India. The kingdom of Magadha was formed in 7th century BC, consisting of the Bihar and Bengal regions. It was one of the four main kingdoms of India at the time of Mahavira and the Buddha, and consisted of several Janapadas. During the rule of Maurya dynasty, the Magadha Empire extended over nearly all of South Asia, including Afghanistan and parts of Persia under Ashoka the Great in the 3rd century BC.
One of the earliest foreign references to Bengal is a mention of a land named Gangaridai by the Ancient Greeks around 100 BC. The word is speculated to have come from Gangahrd (Land with the Ganges in its heart) in reference to an area in Bengal. Bengal had overseas trade relations with Suvarnabhumi (Burma, Lower Thailand, Lower Malay Peninsula, and the Sumatra). According to Mahavamsa, Vijaya Singha, a Vanga prince, conquered Lanka (modern day Sri Lanka) and gave the name "Sinhala" to the country.
From the 3rd to the 6th centuries AD, the kingdom of Magadha served as the seat of the Gupta Empire. The first recorded independent king of Bengal was Shashanka, reigning around early 7th century. After a period of anarchy, the Buddhist Pala dynasty ruled the region for four hundred years, followed by a shorter reign of the Hindu Sena dynasty. Islam made its first appearance in Bengal during the 12th century when Sufi missionaries arrived. Later, occasional Muslim raiders reinforced the process of conversion by building mosques, madrassas and Sufi Khanqah. Beginning in 1202 a military commander from the Delhi Sultanate, Bakhtiar Khilji, overran Bihar and Bengal as far east as Rangpur, Bogra and the Brahmaputra River. Although he failed to bring Bengal under his control, the expedition managed to defeat Lakshman Sen and his two sons moved to a place then called Vikramapur (present-day Munshiganj District), where their diminished dominion lasted until the late 13th century.
During the 14th century, the former kingdom became known as the Sultanate of Bengal, ruled intermittently with the Sultanate of Delhi. Hindu states continued to exist in the Southern and the Eastern parts of Bengal till the 1450s such as the Deva dynasty. Also, the Ganesha dynasty began with Raja Ganesha in 1414, but his successors converted to Islam. Bengal came once more under the control of Delhi as the Mughals conquered it in 1576. There were several independent Hindu states established in Bengal during the Mughal period like those of Maharaja Pratapaditya of Jessore and Raja Sitaram Ray of Burdwan. These kingdoms contributed a lot to the economic and cultural landscape of Bengal. Extensive land reclamations in forested and marshy areas were carried out and intrastate trade as well as commerce were highly encouraged. These kingdoms also helped introduce new music, painting, dancing and sculpture into Bengali art-forms as well as many temples were constructed during this period. Militarily, these served as bulwarks against Portuguese and Burmese attacks. Many of these kingdoms are recorded to have fallen during the late 1700s. While Koch Bihar Kingdom in the North, flourished during the period of 16th and the 17th centuries as well as weathered the Mughals also and survived till the advent of the British.
European traders arrived late in the fifteenth century. Their influence grew until the British East India Company gained taxation rights in Bengal subah, or province, following the Battle of Plassey in 1757, when Siraj ud-Daulah, the last independent Nawab, was defeated by the British. The Bengal Presidency was established by 1765, eventually including all British territories north of the Central Provinces (now Madhya Pradesh), from the mouths of the Ganges and the Brahmaputra to the Himalayas and the Punjab. The Bengal famine of 1770 claimed millions of lives. Calcutta was named the capital of British India in 1772. The Bengal Renaissanceand Brahmo Samaj socio-cultural reform movements had great impact on the cultural and economic life of Bengal. The failed Indian rebellion of 1857 started near Calcutta and resulted in transfer of authority to the British Crown, administered by the Viceroy of India. Between 1905 and 1911, an abortive attempt was made to divide the province of Bengal into two zones. Bengal suffered from the Great Bengal famine in 1943 that claimed 3 million lives.
Bengal played a major role in the Indian independence movement, in which revolutionary groups such as Anushilan Samiti and Jugantar were dominant. Armed attempts against the British Raj from Bengal reached a climax when Subhash Chandra Bose led the Indian National Army from Southeast Asia against the British. When India gained independence in 1947, Bengal was partitioned along religious lines. The western part went to India (and was named West Bengal) while the eastern part joined Pakistan as a province called East Bengal (later renamed East Pakistan, giving rise to independent Bangladesh in 1971). Both West and East Bengal suffered from large refugee influx during the partition in 1947, leading to the political unrests later on. The partition of Bengal entailed the greatest exodus of people in Human History. Millions of Hindus migrated from East Pakistan to India and thousands of Muslims too went across the borders to East Pakistan. Because of the immigration of the refugees, there occurred the crisis of land and food in West Bengal; and such condition remained in long duration for more than three decades.The politics of West Bengal since the partition in 1947 developed round the nucleus of refugee problem. Both the Rightists and the Leftists in the Politics of West Bengal have not yet become free from the socio-economic conditions created by the partition of Bengal. These conditions as have remained unresolved in some twisted forms have given birth to local socio-economic, political and ethnic movements.
In 1950 the Princely State of Cooch Behar merged with West Bengal after King Jagaddipendra Narayan had signed the Instrument of Accession with India. In 1955, the former French enclave of Chandannagar, which had passed into Indian control after 1950, was integrated into West Bengal; portions of Bihar were subsequently merged with West Bengal.
During the 1970s and 1980s, severe power shortages, strikes and a violent Marxist-Naxalite movement damaged much of the state's infrastructure, leading to a period of economic stagnation. The Bangladesh Liberation War of 1971 resulted in the influx of millions of refugees to West Bengal, causing significant strains on its infrastructure. The 1974 smallpox epidemic killed thousands. West Bengal politics underwent a major change when the Left Front won the 1977 assembly election, defeating the incumbent Indian National Congress. The Left Front, led by Communist Party of India (Marxist), governed for the state for the subsequent three decades.
The state's economic recovery gathered momentum after economic reforms in India were introduced in the mid-1990s by the central government, aided by election of a new reformist Chief Minister Buddhadeb Bhattacharya in 2000. As of 2007, armed activists have been organising minor terrorist attacks in some parts of the state, while clashes with the administration are taking place at several sensitive places on the issue of industrial land acquisition. While West Bengal has made economic gains recently, it still remains one of the most poorest states in India due to high political instability and bad governance. Throughout its political and cultural history the state has witnessed strikes/bandhs, a low Human Development Index level, abysmal medical treatment and healthcare services, tremendous lack of socio-economic development, poor infrastructure,excessive corruption and violence.