The history of Bengal is intertwined with the history of the broader Indian subcontinent and the surrounding regions of South Asia and Southeast Asia. It includes modern-day Bangladesh and the Indian states of West Bengal, Tripura and Assam's Karimganj district, located in the eastern part of the Indian subcontinent, at the apex of the Bay of Bengal and dominated by the fertile Ganges delta. The region was known to the ancient Greeks and Romans as Gangaridai, a powerful kingdom whose war elephant forces led the withdrawal of Alexander the Great from India. Some historians have identified Gangaridai with other parts of India. The Ganges and the Brahmaputra rivers act as a geographic marker of the region, but also connects the region to the broader Indian subcontinent. Bengal, at times, has played an important role in the history of the Indian subcontinent.

The area's early history featured a succession of Indian empires, internal squabbling, and a tussle between Hinduism and Buddhism for dominance. Ancient Bengal was the site of several major Janapadas (kingdoms), while the earliest cities date back to the Vedic period. A thalassocracy and an entrepôt of the historic Silk Road, ancient Bengal had strong trade links with Persia, Arabia and the Mediterranean that focused on its lucrative cotton muslin textiles. The region was a part of several ancient pan-Indian empires, including the Mauryans and Guptas. It was also a bastion of regional kingdoms. The citadel of Gauda served as capital of the Gauda Kingdom, the Buddhist Pala Empire (eighth to 11th century) and Sena Empire (11th–12th century). This era saw the development of Bengali language, script, literature, music, art and architecture.

The Muslim conquest of the Indian subcontinent absorbed Bengal into the medieval Islamic and Persianate worlds. Between the 1204 and 1352, Bengal was a province of the Delhi Sultanate. This era saw the introduction of the taka as monetary currency, which has endured into the modern era. An independent Bengal Sultanate was formed in 1352 and ruled the region for two centuries, during which a distinct form of Islam based on Sufism and the Bengali language emerged and the region was known as a major trading nation in the world. The ruling elite also turned Bengal into the easternmost haven of Indo-Persian culture. The Sultans exerted influence in the Arakan region of Southeast Asia, where Buddhist kings copied the sultanate's governance, currency and fashion. A relationship with Ming China flourished under the sultanate.

The Bengal Sultanate was notable for its Hindu aristocracy, including the rise of Raja Ganesha and his son Jalaluddin Muhammad Shah as usurpers. Hindus served in the royal administration as prime ministers and poets. Under the patronage of Sultans like Alauddin Hussain Shah, Bengali literature began replacing the strong influence of Sanskrit in the region. Hindu principalities included the Kingdom of Mallabhum, Kingdom of Bhurshut and Kingdom of Tripura; and the realm of powerful Hindu Rajas such as Pratapaditya, Kedar Ray and Raja Sitaram Ray.

Following the decline of the sultanate, Bengal came under the suzerainty of the Mughal Empire, as its wealthiest province. Under the Mughals, Bengal Subah rose to global prominence in industries such as textile manufacturing and shipbuilding, its economy in the 18th century exceeding in size any of Europe's empires. This growth of manufacturing has been seen as a form of proto-industrialization, similar to that in western Europe prior to the Industrial Revolution. Bengal's capital Dhaka is said to contained over a million people.

The gradual decline of the Mughal Empire led to quasi-independent states under the Nawabs of Bengal, subsequent to the Maratha invasions of Bengal, and finally the conquest by the British East India Company.

The East India Company took control of the region from the late 18th century. The company consolidated their hold on the region following the battles of Battle of Plassey in 1757 and Battle of Buxar in 1764 and by 1793 took complete control of the region. Capital amassed from Bengal by the East India Company was invested in various industries such as textile manufacturing in Great Britain during the initial stages of the Industrial Revolution. Company policies in Bengal also led to the deindustrialization of the Bengali textile industry during Company rule. Kolkata (or Calcutta) served for many years as the capital of British controlled territories in India. The early and prolonged exposure to the British colonial administration resulted in the expansion of Western-style education, culminating in development of science, institutional education, and social reforms in the region, including what became known as the Bengali Renaissance. A hotbed of the Indian independence movement through the early 20th century, Bengal was partitioned during India's independence in 1947 along religious lines into two separate entities: West Bengal—a state of India—and East Bengal—a part of the newly created Dominion of Pakistan that later became the independent nation of Bangladesh in 1971.