Bangladesh has a history of deadly tropical cyclones. A cyclone in 1876 killed at least 100,000 people, and another cyclone in 1897 killed 175,000 people. On November 12, 1970, a cyclone struck Bangladesh, then known as East Pakistan, producing a storm surge that killed at least 300,000 people. This made it the deadliest tropical cyclone on record. The cyclone wrecked about 400,000 houses, 99,000 boats, and 3,500 schools. The local government's lack of response to the storm was a partial factor in the Bangladesh Liberation War, one of the first instances in which a natural disaster led to a civil war. After the storm, Bangladesh instituted a Cyclone Preparedness Programme to better inform residents of approaching storms, construct more shelters, and restore coastal mangrove forests to mitigate storm surge flooding. Another powerful cyclone struck the country in 1991, killing 138,000 people and displacing around 10 million people homeless, with more than 1 million homes destroyed. In 2007, a similarly strong Cyclone Sidr struck the country, killing 3,406 people. The reduced death toll, compared to the 1970 and 1991 storm, was partially due to the improved warning systems and more shelters.