This is a question that is still being debated by many experts. One of the beliefs is that Chief Powhatan spared John Smith's life because he hoped to form an alliance with the settlers in Jamestown and have their support in fighting other Native American nations. Some people believe that Chief Powhatan's 11-year old daughter Pocohontas intervened, but this has never been proven.
Chief Powhatan did keep John Smith living within the tribe for approximately four weeks. During that time, no one has documented exactly what happened.