Photos: Shia, Sunni brothers participate in flag hoisting ceremony on Eid Milad-un-Nabi in Karachi, Pakistan

Islamic Unity Week is a period of one week between Rabi' al-Awwal 12 (Prophet's birthday according to Sunnis) and Rabi' al-Awwal 17 (Prophet's birthday according to Shi'as). This period was named as "the Week of Unity between Shi'a and Sunnis" by Imam Khomeini on November 1981. The idea of naming this period as above was given and celebrated for the first time by Ayatollah Khamenei in 1978. In some countries, some programs are held in order to bring unity between the two religions. (Wikishia)