Bangladesh, meaning "Bengal nation," is a low-lying country formed by the alluvial plain of the Ganges-Brahmaputra river system—the largest delta in the world. The rivers' annual floods bring silt to renew farmland fertility, often creating new islands in the delta that are quickly claimed as farmland. Much of the land is barely above sea level, with the exception of hills east and south of Chittagong. The monsoon winds come in summer (June to September) and bring heavy rainfall and cyclones. Bangladesh is one of the poorest countries on Earth, and most people are subsistence farmers.

Supported by India, East Pakistan became Bangladesh in 1971 after a war of independence against Pakistan. Bangladesh has the third largest Muslim population in the world after Indonesia and Pakistan. With more than 1,000 people per square kilometer (2,600 per square mile), the country is one of the most crowded on earth. Poverty is widespread, and almost half of all Bangladeshis live on less than $1 a day.

Rich soils yield three rice harvests a year, but major cyclones cause storm surges that smash into the delta, sweeping people, livestock, and crops from the lowlands. In 1970 a cyclone killed more than 300,000 people along the coast, and in 2007 Cyclone Sidr caused thousands of deaths along with significant damage to the country's infrastructure.

Monsoon rains also cause frequent flooding of Bangladesh's lowlands. On average, about one-third of the country floods during the rainy season. Earthquakes, droughts, and landslides also occur.

Deforestation in upper watersheds of the Ganges and Brahmaputra Rivers worsens flooding downstream. The government protects the Sundarbans mangrove forest—one of the largest in the world and home to threatened species like the Bengal tiger.