A simple cotton bag, so-called Pilgrim or Beggar bag. There are many exemplars, represented on medieval art, specially on illuminated mansucripts.
A handy item for transporting your personal belongs during a reenactment, or during a hikking march.
Although this bag could be valid for several epoques, from Early Middle Ages to Renaissance, this complement was commonly used by pilgrims and shepperds until the modern days.