Plains Indians used numerous effective ways to communicate over long distances. In earlier times (before the use of trade mirrors), smoke signals were very understandable for distances as far as thirty miles. A small, smoky fire of sticks, green or damp grass, and dried buffalo dung worked perfectly, as long as the wind wasn’t too severe. A blanket or buffalo robe was laid over the fire to trap the smoke, then it was released in short or long columns, or in individual puffs. Many of the signals were commonly used and understood by all tribes, such as one puff meaning “an enemy is in the area”, two puffs meaning “we are camping here” or three puffs meaning “help or danger".