Lions once ranged across the African continent and into Syria, Israel, Iraq, Iran and Pakistan. A variety of factors—ecological changes, urbanization and deforestation, regional wars, and retaliation for livestock killing has drastically reduced their numbers. Two thousand years ago an estimated one million lions roamed the Earth. By the 1940s, the number was less than half that and it has declined precipitously since then. Today, there may be fewer than 20,000 lions left.