Nayrouz is a Coptic Orthodox festival honoring martyrs and confessors. It marks the start of the Coptic New Year and is celebrated on September 11. It used to be popular among both Christians and Muslims in Egypt, but lost significance due to government repression. The festival has a long history and was often suppressed in medieval Cairo, but survived in Upper Egyptian villages. https://en.wikipedia.org/wiki/Nayrouz