Displaced Sunni Iraqis, who fled the violence in Ramadi, arrive at a makeshift camp on the outskirts of Baghdad, in April. Ahmad Al-Rubaye/AFP/Getty Images hide caption
Shiites
Yemen's President Abed Rabbo Mansour Hadi speaks during the opening meeting of the Arab Summit in Sharm el-Sheikh, south of Cairo, on Saturday. Reuters/Landov hide caption
A wounded girl reacts as she is carried by a man out of a mosque that was attacked by a suicide bomber in Sanaa, Yemen, on Friday. Khaled Abdullah/Reuters/Landov hide caption
Shiite fighters and Sunni fighters, who have joined Shiite militia groups known collectively as Hashid Shaabi ("Popular Mobilization") to fight the Islamic State, gesture Tuesday next to former Iraqi President Saddam Hussein's palaces in the Iraqi town of Ouja, near Tikrit. Thaier Al-Sudani/Reuters/Landov hide caption
In Tikrit Offensive, Local Sunnis, Shiite Militias Are Unlikely Allies
Mourners carry the coffin of a victim of a bomb attack on a Baghdad cafe on Tuesday. Violence in Iraq has spiked this year. The bodies of 18 men were found Friday in a Sunni area near Baghdad. Sabah Arar/AFP/Getty Images hide caption
Pakistanis check the site of a bomb blast in Karachi on Sunday. Pakistani officials say the blast has killed dozens of people in a neighborhood dominated by Shiites. Fareed Khan/AP hide caption
A fresco painting from the Chehel Sotun Pavillion in Isfahan, Iran, depicts Persian warfare during the Safavid dynasty period. Dave Bartruff/Corbis hide caption