Bandō is the old name for what is now the Kantō region,[1] used in this case because the temples are all in the Prefectures of Kanagawa, Saitama, Tokyo, Gunma, Ibaraki, Tochigi and Chiba.
As is the case with all such circuits, each location has a rank, and pilgrims believe that visiting them all in order is an act of great religious merit.
[1] Started by Minamoto no Yoritomo and his son Sanetomo, the Bandō Sanjūsankasho is just one of 70 different Kannon pilgrimage circuits existing in Japan, each including 33 temples because the goddess is believed to have 33 different manifestations.
Even though women were allowed to pray at individual temples, the circuit was originally reserved to male pilgrims.
[1] Pilgrims leave behind a slip of paper or a sticker as a proof of their visit, and many of these can be seen plastered on temple walls and pillars.