A mysterious phenomenon rocked the southern coast of Bangladesh in the 19th century. It was a phenomenon which was experienced by hundreds and thousands of people but nobody could identify its actual cause. It is still regarded as one of the top unsolved mysteries of the world. This phenomenon was named Barisal Guns after Bangladesh's Barisal city, whose dwellers first documented this incident. This phenomenon refers to a series of deafening loud sounds that rocked Bangladesh's southern coast without any earthquake or without any incident of associated explosion. It was first documented in 1870 AD in the district gazetteer of Barisal. The then British administration, at first, considered those as explosions from cannon fires. But repeated investigations did not find any major battle which could produce such a loud sonic boom. According to Asiatic Society reports, this sonic boom had been heard by the inhabitants of Noakhali, Khulna, Barisal and even in Narayanganj. Various witness accounts informed that sometimes it was only one loud bang and sometimes repeated loud bangs used to create panic among local inhabitants, however, no hazardous outcome had been reported after the phenomenon. Eminent poet Sufia Kamal also mentioned this phenomenon in her autobiography where she says that this mysterious bang was last heard in the early 1950s. According to one theory, the sonic boom was created by sound waves which were broken up by the local topography, but this theory could not be proved. This incident is now considered as an example of skyquake—which refers to an unexplained sonic boom without any corresponding earthquake.