Black Lagoon takes place in a modern-day Earth, in the early 1990's, based primarily in Central and South America, Southeast Asia and Japan. The Thai city of Roanapur serves as the main backdrop of the majority of the world's story. The remainder of the world seems to follow traditional history, though it's not clear when in the 1990's the setting is placed in. The political layout of Black Lagoon, likewise, is probably similar to Earth leading up to and during the Gulf War. The criminal underworld is the main backgroud of Black Lagoon, which runs from the Italian and Russian Mafia, the Chinese Triads to the South and Central American cartels.