1 : Smoke Signal -

Report: The History and Application of Smoke Signals The smoke signal is one of the oldest forms of long-distance visual communication, used by diverse cultures throughout history to transmit news, signal danger, or gather people. While often associated with Native American tribes, it has been used by ancient civilizations in China, Greece, and Rome. Historic Use and Origins

: The earliest recorded use dates to the 8th century BC. Soldiers along the Great Wall of China used smoke to signal imminent danger or enemy movements. 1 : Smoke Signal

: Tribes such as the Apache and Coeur d'Alene developed precise signaling methods using damp grass to create thick columns of white smoke. Report: The History and Application of Smoke Signals