The martyrdom of Imam Al-Hussein at Karbala in 680 A.D was a defining moment for the creation of a distinct Shi’a identity. This tragedy had a greater impact on Shi’ism than any other event in Islamic history and has been described as a ‘root metaphor’ around which Shi’a religious beliefs and practices are grounded. Although the controversial issue of the succession of Imam Ali led to the initiation of Shi’a partisanship, it was the Karbala tragedy that gave impetus to create a distinct Shi’a identity that could be distinguished from other mainstream outlooks in Islam. The way in which this clear distinction manifested itself after the events of Karbala can be assessed from the way sectarian identities became firmly demarcated in the Muslim community of Kufa, for example, after this event. The centrality and importance of Karbala, in the ideological and geographical context, was also affirmed by the traditions of the later Imams and it’s significance can be further assessed by the evolution of distinctly Shi’a rituals informed by it. The rituals that came to be associated with the Karbala tragedy played a defining role in the creation of a distinct Shi’a identity and a political sensibility by becoming a central ‘vehicle of expression’ for this identity. 
Segregation of Sacred Space in the Aftermath of the Tragedy of Karbala:
An overview of the earlier diversity of sacred space and its later segregation provides an instructive insight into the way the tragedy of Karbala had played a crucial impact on what came to characterized as a distinct Shi’a identity. Before the events of Karbala, there seemed to be porous demarcations of sectarian boundaries and identities in Islam. Various tribes had loose sectarian inclinations but most Muslims followed their clan’s tribal affiliations. However, such sectarian tribal affiliations did not lead to the classification of religious spaces as being Shi’a or Sunni. Although sectarian affiliations existed, people from a range of sectarian inclinations prayed at the same venue in their own distinct ways in the 7th century Kufa, for example. Given that this situation changed by the 8th century within two decades of the battle of Karbala, it is clearly probable that the tragedy of Karbala created new ‘religious geographies’ in its aftermath which delineated a clear distinction between ‘friendly/sacred’ and ‘hostile/accursed’ spaces. Although a transformation towards the consolidation of sectarian identity had started taking place in the mid 7th century when ritual practices began to eclipse tribal affiliations  it was in the post-Karbala milieu when ‘some mosques were renovated to celebrate the death of al-Hussein’ that some religious spaces became safe havens for the Shi’a while other became openly hostile. In this way it was in the aftermath of this tragedy that by segregation of spaces a Shi’a identity seems to have been consolidated.
Karbala Rituals as Vehicles of Expression of the Shi’i Identity:
The segregation of sacred spaces is indicative of the fact that a paradigmatic change occurred in the Shi’i character with the development of a distinct set of rituals that were developed and formalized after Imam Hussein’s martyrdom. These rituals, which started immediately after the event became a novel and powerful public affirmation of the Shi’i identity, while serving as a unique medium for expressing and strengthening a variety of political and social identities, associations and relationships. So much so that the ‘potency of the practice’ came to overshadow matters of theology. To this day it is the martyrdom of Imam Hussein that is celebrated most fervently in entire the Shi’a calendar. The myths of Karbala, woven together with historical facts introduced a devotional aspect into Shi’ism and created the ethos of the popular Shi’a personality. They also played a crucial role in creating and consolidating the Shi’a identity and set it apart from other sectarian inclinations. Such rituals manifestly distinguish Shi’ism from Sunnism, because differences between them on ideological constructs are rather insignificant.  The institution of mourning for the martyred Imam came to symbolize the ethos of Shi’ism and became a conduit for articulating the ‘revolutionary’ message of Shi’ism against perverse socio-political conditions that negated the Islamic ideal. The mourning rituals held during Muharram and the ensuing months provided crucial opportunities for the development of social networks among Shi’as while fostering a sense of unity for the community identity.
Imam Hussein’s sacrifice also gave Shi’i Islam an ‘ethos of sanctification through martyrdom’ which did not exist earlier. Although the Shi’as were persecuted all through their early history and according to the Shi’a traditions all the Imams faced persecution and were martyred, it was the martyrdom of Hussein that has given this distinct characteristic to Shi’i Islam. Rituals provided an intrinsic channel to articulate the devotion of the Prophet’s family. For the Shi’i the primacy of the Ahlebayt was utmost and this was a singular event which symbolized the highest form of injustice meted out to the family of the Prophet. In a way, consequently, Shi’ism unwittingly appropriated the claims to affection of the Ahle Bayt by giving utmost importance to their reverence through such rituals and formulating an identity around them.
Pilgrimage and The Religious Geography of Karbala:
Among the various rituals that emerged in the aftermath of al-Hussein’s martyrdom , the pilgrimage to Karbala and the resting places of other Imams was a tradition that came to signify a specific Shi’a outlook. Many traditions from the Shi’a Imams point to the importance placed on a pilgrimage to Karbala for strengthening the communal identity and consequently extensive pilgrimage manuals were developed which were significant in articulating the Shi’i identity. These acts of pilgrimage became integral and necessary to the Shi’i identity after the 7th century, a fact which points to the importance being attached after the Karbala tragedy. According to a tradition by Imam Jafar as-Sadiq, a person who failed to visit al-Hussein at Karbala had ‘departed from a claim of God’ because the ‘the claim of Hussein is a mandatory duty from God and is an obligation upon every Muslim’. In a many ways pilgrimage to Karbala was almost elevated to the rank of the pilgrimage of Hajj the Shi’ite traditions . In another tradition from Imam Hasan al-Askari, a pilgrimage to Karbala after forty days after the anniversary of Hussein’s death is described as ‘a sign of a true believer’ and as one of the distinct characteristics of a Shi’i which distinguishes them from the general Muslim population. Therefore the centrality of such pilgrimage was seen as being integral to the construction of the Shi’a identity.
Crystallization of Political Sensibilities:
Before the Battle of Karbala took place various tribes held loose sectarian inclinations. But a tribe, which for example supported Imam Ali politically, did not necessarily come to be designation as ‘Shia’ and such sectarian tribal affiliations did not lead to the classification of religious identity as being exclusively either Shia or Sunni (Haider 2011: 238). Subtle sectarian identities, it must be emphasized therefore, existed primarily as a consequence of political loyalties rather than any manifest theological differences. The fact that some Muslims sided with Ali, can therefore be explained only in the terms of socio-political reasons, not on the basis of theological teachings. Such socio‑political influences did however lead to later differences and a theological bifurcation on the interpretation and implementation of the tenets of the faith.
The Battle of Karbala manifestly enhanced the solidarity amongst the Shi’ites and renewed their political agency because it provided a clear vindication of Shi’ism claims against the ‘injustices’ of Sunnism against the Prophets family and underlined the ‘moral corruption’ and ‘political repression’ of their political elites. The symbolism of Karbala as the revolt of the oppressed against oppressors, staged against tyranny, injustice, and repression had an everlasting impact on the Shi’a psyche. In the immediate aftermath of the Karbala tragedy this renewed sense of agency constituted the prelude to a series of Shi’ite revolts against the Ummayads.
Imam Hussein’s refusal to compromise with ‘godlessness’ and ‘tyranny’, with an outlook that did not ‘see death but as happiness, and living with tyrants but as sorrow’, saved the Muslims from having to adhere to a ‘pseudo-religion’. After Karbala Imam Hussein has emerged as the ‘most revered and meritorious martyr’ the world has produced and in this sense ‘he lost the battle but won the campaign’ and his martyrdom has possibly brought a paradigmatic shift in the political consciousness of the Shi’a community and left a lasting impact on the construction of the Shi’i identity. Given these aspects it seems clear that the tragedy of Karbala is a central narrative in the Shi’a history that manifest informs and consolidates the Shi’a identity.
Vaglieri, Veccia. Al-Ḥusayn b. Alī b. Abī Ṭālib, (online resource)
Chittick, William. A Shi’ite Anthology, 137-40.
Aghaie, Kamran Scott. The Martyrs of Karbala, 3-14.
Al-Mufīd, Kītāb al-irshād, transl. I. K. Howard, 296-99 (Bio) and 346-72 (Account of Karbala)
Bahr-ul-Uloom, The Tale of the Martyrdom of Imam Hussain, 15-21, 68-77
Haider, Najam. Origins of the Shia: Identity, Ritual and Sacred Space in Eighth Century Kufa.
 Aghaie .The Martyrs of Karbala, 3-14
 Haider. Origins of the Shia: Identity, Ritual and Sacred Space in Eighth Century Kufa 232-234
 Ibid. 231
 Ibid. 235
 Ibid .241
 Aghaie .The Martyrs of Karbala, 3-14
 Haider. Origins of the Shia: Identity, Ritual and Sacred Space in Eighth Century Kufa 231
 Chittick A Shi‗ite Anthology, 137-40
 Aghaie. The Martyrs of Karbala, 3-14
 Mufid, Kitab al Irshad. transl. I.K Howard. 346-72 (Account of Karbala), Chittick. A Shi’ite Anthology.
 Aghaie The Martyrs of Karbala, 3-14
 Mufid. Kitab al Irshad. transl. I.K Howard. 346-72 (Account of Karbala)
 Haider. Origins of the Shia: Identity, Ritual and Sacred Space in Eighth Century Kufa.245-246
 Haider. Origins of the Shia: Identity, Ritual and Sacred Space in Eighth Century Kufa .245-246
 Mufid, Kitab al Irshad. transl. I.K Howard. 346-72 (Account of Karbala)
 veccia Vaglieri, Al-Ḥusayn b.Alī b. Abī Ṭālib, (online resource), Bahr ulUloom, 68-77
 BahrulUloom, The Tale of the Martyrdom of Imam Hussain. 15-21