A Manji is a Sikh religious administrative unit. It was founded by Guru Amar Das, the third leader of Sikhism. Manji refers to each zone of religious administration with an appointed chief called sangatias, with officially appointed representatives known as masand. It has been conceptually similar in its aims to the diocese system in Christianity, and has been similarly important in Sikh missionary activity.
The word Manji or Manja literally means a cot (taken as the seat of authority in this context).
References
Sikh Manji Wikipedia(Text) CC BY-SA