One cannot understand Iraq’s modern relationship with Iran without looking at its historic roots, for its history is at the religious, social and psychological heart of the relationship, and is tied to highly complex geopolitics and demographic realities. However, examining the past alone will not bring one to any logical understanding of today’s reality, for one must always take into consideration the real-time factors of social mobility and advancing private interests that influence the political tack of nations.

The historical roots of the complex dynamics that pervade the relationship between these two countries and peoples run deep, all the way back to the Sassanid era. During this period, Mesopotamia was under the rule of an ancient empire that controlled the known world for a few thousand years. It selected Ctesiphon, not far from Baghdad, as its capital for centuries. However contributing geographic factors created a cultural conflict, stemming from the fact the lands of Iraq gave birth to civilizations and empires that influenced the value systems of that ancient world.

When the Muslim armies marched into Iraq, and subsequently annexed the Persian lands to their fledgling empire, the conflict began to take on different dimensions. Persian identity persisted within the Islamic civilization, but it transformed into an identity that mirrored and overlapped with Arab identity. Islamic culture could not acknowledge the struggle between the two competing identities, and preferred instead to blot out tribal identities with a unifying Islamic identity, exemplified in the famous phrase, "There is no difference between an Arab and a Persian, except in piety."

Iran officially became Shiite at the hands of Ismail the Safavid in the mid-15th century. He initiated a new phase of sectarian diversification within Islam. Since then, Iraq has been polarized between Safavid Shiite rulers and Sunni Ottomans, who considered themselves heirs of the Ottoman Empire. The power struggle often boiled over into bloody battles and wars in which the lands of Iraq carried strategic importance, and defending Iraq's Sunnis or its Shiites was the rallying cry for each of the rival factions.