In the medieval period Baghdad, the “city of peace” founded by the Abbasid Caliph al-Mansur in 762, experienced a high number of popular revolts. The latter either opposed different popular factions, or a social group to the government. In the Sejukid period alone, around sixty cases of “fitan” ("fitna" refers to an episode of violence initiated by the urban population) have been noted in the medieval sources. This paper investigates a certain type of “fitna”, that which took place between Sunnis and Shi'a, and particularly between the Sunni neighbourhood of Bab al-Basra and the (mostly Shi‘i populated) neighbourhood of al-Karkh. A micro history of social relations within the city, the paper examines a number of Arabic primary sources produced in the medieval period by historians, bureaucrats, and religious scholars, among which: the journal of Ibn al-Bannā’ (translated and edited by Makdisi); Ibn al-Jawzī (Kitāb al-Muntaẓam); Ibn al-Athīr (Al-Kāmil fī al-Tārīkh); Ibn al-Sā‘ī (Tārīkh al-Khulafā’ al-‘Abāssiyin); Ibn Kathīr (Al-Bidāya wa al-Nihāya); Sibt ibn al-Jawzī (Mir’āt al-Zamān). In terms of methodology, I have selected a few case studies to be analysed, many of which took place under different political rule: 946, 965, 1030, 1056, 1069, 1089, and 1256. What are the most common causes the medieval writers ascribe to these violent episodes? Can we establish patterns of violence in the city, particularly under a specific ruler (Buyid, Seljuk) or caliph? To what extent was violence an outcome of political decisions? When and how was the local population affected by intellectual debates through the role of local preachers and religious scholars? How did sultans and caliphs cooperate when sending their troops to appease the tensions? The paper argues that the sectarian clashes in Baghdad between the Bab al-Basra and al-Karkh quarters had a variety of factors, the most common being the freedom to perform certain Shi'i rituals in the city such as ‘Ashura’, which was encouraged under Buyid rule and banned under the Seljuks. Political rulers had a particularly critical influence on social peace – the rule of Caliph al-Nasir (1180-1225) saw a significant drop in violence. On a historiographical level, this research sheds light on the different ways in which the historical chronicles, biographical dictionaries, and theological treatises deal with these episodes and how they describe them. In theological treatises for example, these examples of sectarian conflict often serve to underline a point on theology and orthodoxy.