The Samanas are a part of Siddhartha's early life. Actually, Siddhartha began life as a Brahman, but felt unfulfilled and, therefore, decided to seek enlightenment. Along with a friend, Siddhartha leaves home and joins a group of severe wanderers called the Samanas who are known to many as "wandering ascetics."
The life with the Samanas is described as a life of complete self-denial. They dislike everything sensual. As a result, Siddhartha tries to get rid of his desires, but he is unable to and remains dissatisfied. The Samanas are described as being interested in both yoga and asceticism; however, those two things seem to be leading Siddhartha away from his own truth.
Wisdom cannot be imparted. Wisdom that a wise man attempts to impart always sounds like foolishness to someone else ... Knowledge can be communicated, but not wisdom. One can find it, live it, do wonders through it, but one cannot communicate and teach it.
Through this experience, Siddhartha decides that the Samanas are looking for enlightenment just as much as he is. As a result, it is Siddhartha's decision to JOIN the Samanas, but it is also his own decision to LEAVE the Samanas after three years and listen to the teachings of Buddha.