Most Iranian people are Muslims. Therefore, many Iranian culture and customs are Islamic ones. The most specific religious custom in Iran is the mourning of Muharram. Muharram is the first month of the Islamic calendar in which the battle of Karbala took place. In this battle, the forces of the second Ummayad caliph killed Imam Hussein ibn Ali, the grandson of Prophet Muhammad. Muslims believe that Imam Hussein fought for justice and the caliph killed him brutally, so they mourn for Imam Hussein every year at the time that battle of Karbala happened. There are many different rituals in the Islamic countries for this mourning. If you are interested in experiencing new spiritual rites and intend to visit Iran, consider planning your trip in Muharram.
The most common rite in Muharram is Rawsa or Rowzeh. Rowzeh is a ritual in which people listen to Noha and beat their chests to display their grief for Imam Hussein. Noha is a poem and story about the events in the battle of Karbala and the death of Imam Hussein which a person reads in a plaintive voice. While listening to Noha Shia people weep for Imam Hussein as much as they can to offer their condolences to his family.