Bengal ( ben-GAWL; Bengali: বাংলা/বঙ্গ, romanized: Bānglā/Bôngô, pronounced [ˈbɔŋgo] (listen)) is a geopolitical, cultural and historical region in South Asia, specifically in the eastern part of the Indian subcontinent at the apex of the Bay of Bengal, predominantly covering present-day Bangladesh and the Indian state of West Bengal. Geographically, it consists of the Ganges-Brahmaputra delta system, the largest river delta in the world and a section of the Himalayas up to Nepal and Bhutan. Dense woodlands, including hilly rainforests, cover Bengal's northern and eastern areas, while an elevated forested plateau covers its central area; the highest point 3,636 metres (11,929 ft) is at Sandakphu. In the littoral southwest are the Sundarbans, the world's largest mangrove forest. The region has a monsoon climate, which the Bengali calendar divides into six seasons.

Bengal, then known as Gangaridai, was a leading power in ancient South Asia, with extensive trade networks forming connections to as far away as Roman Egypt. The Bengali Pala Empire was the last major Buddhist power in the subcontinent, founded in 750 CE and becoming the dominant power in the northern Indian subcontinent by the 9th century CE. It was replaced by the Hindu Sena dynasty in the 12th century. Islam had been introduced during the Pala Empire, through trade with the Abbasid Caliphate; it spread across Bengal following the formation of the Delhi Sultanate. The region reached its highest prosperity under the Bengal Sultanate, founded in 1352, which became one of the world's richest trading nations.

Absorbed into the Mughal Empire in 1576, the Bengal Subah was the empire's wealthiest province, and became a major global exporter, and center of industries such as cotton textiles, silk, and shipbuilding. Its economy was worth 12% of the world's GDP, a value bigger than the entirety of Western Europe, and its citizens' living standards were among the world's highest. Bengal's economy underwent a period of proto-industrialization during this period. The region was conquered by the British East India Company after the Battle of Plassey in 1757, and became a part of the Bengal Presidency of British India. Bengal made significant contributions to the world's first Industrial Revolution, but later suffered its own deindustrialisation. East India Company policies, such as increasing agriculture tax rates from 10% to up to 50%, alongside drought and epidemics, contributed to famines such as the Great Bengal famine of 1770, which resulted in the deaths of 1 million to 10 million Bengalis.

After World War Two, during which Bengal was invaded by Japan, Bengal played a major role in hosting revolutionary groups of the Indian independence movement. As part of the Partition of India, Bengal was divided between predominantly Muslim and Hindu populations; an independent, united Bengal was considered, but the idea was rejected, predominantly due to religious divisions. West Bengal subsequently became a part of India and East Bengal a part of Pakistan, although it won its independence as Bangladesh in 1971. Today, Bengal is divided between Bangladesh and the Indian state of West Bengal; the historical region encompassed the modern-day states of Bihar, Jharkhand, Odisha, and Assam, among others in India, and some parts of Myanmar or Burma (Rakhine State). The population of Bengal was estimated to be 250 million in 2011, with an estimated 160 million people in Bangladesh and 91.3 million people in India, making it one of the most densely populated regions in the world. The predominant ethnolinguistic group is the Bengali people, who speak the Indo-Aryan language of Bengali. Bengali peoples also have a significant presence in the Indian states of Tripura, Assam, Meghalaya, Mizoram, Nagaland and Uttarakhand, and others.