Diyala is located 60 kilometers northeast of Baghdad, and is considered a “road-knot” between four Iraqi provinces, including Diyala and Sulaymaniyah, Wasit, and Salah al-Din. In addition, roads which pass through Diyala can lead to Anbar province or Mosul. Therefore, any militant group that wants to impose its control over those areas must have a presence in Diyala.
Except for Salah Al-Din, all of these four provinces are adjacent to Iran, and they share with Diyala a similarly rugged geographical terrain. These natural features make Diyala an important place for jihadists to gain a foothold, especially in the Hamrin Mountains. The range extends northwest from Diyala’s border with Iran to the Tigris River, crossing northern Salah al-Din and southern Kirkuk.
Diyala’s inhabitants are Sunni and Shiite Muslims; primarily Arabs and Kurds. As a consequence, the province witnessed sectarian war during conflicts between Shiite militias and al-Qaeda (Sunni) from 2006 to 2008, as well as the birth of the first generation of al-Qaeda in Iraq, whose militants were trained in Diyala’s rugged mountains and valleys. Diyala was also unsurprisingly the last cache for al-Qaeda’s leader in Iraq, Abu Musab al-Zarqawi (aljazeera.net, June 8, 2006). He was killed in an American airstrike in an isolated safe house north of Baghdad in June 2006.
The Islamic State Gains New Operational Foothold in Iraq’s Hamrin Mountains – Jamestown