Stone Age tools dating back 20,000 years have been excavated in the state, showing human occupation 8,000 years earlier than scholars had thought based on prior evidence.The region was a part of the Vanga Kingdom, according to the Indian epic Mahabharata.Several Vedic realms were present in Bengal region, including Vanga, Rarh, Pundravardhana and the Suhma Kingdom.

One of the earliest foreign references to Bengal is a mention by the Ancient Greeks around 100 BC of a land named Gangaridai, which was located at the mouths of the Ganges.Bengal had overseas trade relations with Suvarnabhumi (Burma, Lower Thailand, Lower Malay Peninsula, and the Sumatra).According to the Sri Lankan chronicle Mahavamsa, Prince Vijaya, a Vanga Kingdom prince, conquered Lanka (modern-day Sri Lanka) and gave the name Sinhala Kingdom to the country.

The kingdom of Magadha was formed in 7th century BCE, consisting of the regions now comprising Bihar and Bengal. It was one of the four main kingdoms of India at the time of the lives of Mahavira, founder of Jainism, and Gautama Buddha, founder of Buddhism. It consisted of several janapadas or kingdoms.Under Ashoka, the Maurya Empire of Magadha in the 3rd century BCE extended over nearly all of South Asia, including Afghanistan and parts of Balochistan.From the 3rd to the 6th centuries CE, the kingdom of Magadha served as the seat of the Gupta Empire.

Two kingdoms – Vanga or Samatata and Gauda – are mentioned in some texts to have appeared after the end of Gupta Empire, although details of their ruling time are uncertain.The first recorded independent king of Bengal was Shashanka, who reigned in the early 7th century.Shashanka is often recorded in Buddhist annals as an intolerant Hindu ruler who is noted for his persecution of the Buddhists. Shashanka murdered Rajyavardhana, the Buddhist King of Thanesar, and is noted for destroying the Bodhi tree at Bodhgaya, and replacing Buddha statues with Shiva lingams.After a period of anarchy,the Pala dynasty ruled the region for four hundred years starting from the eighth century. It was followed by a shorter reign of the Hindu Sena dynasty.

Some areas of Bengal were invaded by Rajendra Chola I of the Chola dynasty between 1021 and 1023.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, madrasas and khanqahs. Between 1202 and 1206, Muhammad bin Bakhtiyar Khilji, a military commander from the Delhi Sultanate, 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 defeated Lakshman Sen. His two sons moved to a place then called Vikramapur (present-day Munshiganj District), where their diminished dominion lasted until the late 13th century.

Subsequent Muslim conquests helped spread Islam throughout the region.Consequently, the region was ruled by dynasties of Bengal Sultanate and feudal lords under the Delhi Sultanate for the next few hundred years. Smaller Hindu states, landlords, and Baro-Bhuyans also ruled in parts of Bengal. The Bengal Sultanate was interrupted for 20 years by an uprising by the Hindus under Raja Ganesha. In the sixteenth century, Mughal general Islam Khan conquered Bengal. However, administration by governors appointed by the court of the Mughal Empire gave way to semi-independence of the area under the Nawabs of Murshidabad, who nominally respected the sovereignty of the Mughals in Delhi. Several independent Hindu states were established in Bengal during the Mughal period, like those of Pratapaditya of Jessore District and Raja Sitaram Ray of Bardhaman. The Koch dynasty in northern Bengal flourished during the period of 16th and the 17th centuries; it weathered the Mughals and survived till the advent of the British colonial era.

Several European traders reached this area late in the fifteenth century. Their influence increased into the 18th century, when the British East India Company gained rights to collect revenue in Bengal subah (province) in 1765 as per the treaty between the East India company and Mughal emperor following the Battle of Buxar in 1764. Mir Qasim, the last independent Nawab, was defeated by the British.

The Bengal Presidency was established in 1765; it later incorporated all British territories controlled 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 due to tax policies enacted by the British company.Calcutta, the headquarters of the East India company, was named in 1772 as the capital of British-held territories in India. In 1793 East India company abolished local rule (Nizamat) and annexed the former Mughal province.

The Bengal Renaissance and Brahmo Samaj socio-cultural reform movements had great effects 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, which claimed 3 million lives during World War II.