Shiite Muslims are spread around the world, from the Indian subcontinent to the Arabian Peninsula and the Mediterranean region. They belong to various nationalities, have diverse cultures and sometimes even have different religious doctrines. Historically, they have never been under a single government nor have they enjoyed a single cohesive identity.

But the recent upsurge of anti-Shiite Salafist currents has made Shiites put their differences aside and align along one axis against a common threat.

The doctrinal differences among the various Shiite sub-sects have played a significant role in increasing the distance between them and has sometimes caused quarrels. Zaidi Shiites in Yemen almost completely split from Imami Twelver Shiites in other areas, meaning communication between them was cut off for centuries. Also, differences between the Usuli and Akhbari doctrines led to repeated conflicts in Iraq during the 18th century, sometimes involving violence and leaving casualties on both sides.

After the establishment of the Shiite Islamic regime in Iran, Shiite communities developed differences over such a political system and about the methods and approaches used by the regime’s founders. Religious leaders in Najaf have dissociated themselves from engaging and cooperating with the new Iranian regime because of doctrinal differences over the rightfulness of establishing a religious regime and over the violent methods that the regime sometimes uses.