For centuries the social and political organisation of many Iraqis has centred on the tribe. Socially, tribes were divided into related sub-tribes, which further divided into clans, and then into extended families. Today 75% of Iraq’s people are members of a tribe with a strict honour code. Despite the liberation of most of IS-occupied areas, political differences and a struggle for power remain. There have been clashes between the Popular Mobilisation Units and the Kurdish Peshmerga forces near Kirkuk. Also, on 20 July clashes between the Sunni Nineveh Guards and the Shi’ite faction of Kataib Sayyid al-Shuhada took place in Mosul. There are fears that these clashes might expand into open warfare amid deep differences over the disputed tribal areas extending from the Iranian border, through Kirkuk province and into Yazidi areas near the Syrian border. Terrorists have also been exploiting tribal differences for years. For historical roots, see: