Tal Afar, on which Iraq's controversial Hashed al-Shaabi paramilitary force launched an offensive at the weekend, used to be the main Turkmen town in the country.
A key hub between Mosul and the Syrian border in the Islamic State group's shrinking "caliphate", Tal Afar is now at the heart of a battle for influence between Iraq's powerful neighbours Turkey and Iran.
Here are some key facts about the northwestern town:
Geography and history
The town lies 380 kilometres (240 miles) northwest of the capital Baghdad and about 60 kilometres (40 miles) west of the second city of Mosul.
Tal Afar's history goes back thousands of years and it was once part of the Assyrian empire. It is dominated by an Ottoman-era citadel, which was damaged in 2014 when IS militants blew up some of its walls.
Population Before the Islamic State group took it over in the early days of its June 2014 offensive in Iraq, the town had an estimated population of around 200,000.
The town, a Shiite-majority enclave in the mostly Sunni Muslim area, held out several days after Mosul was seized by the jihadists.
The town's population was overwhelmi ngly Turkmen, one of Iraq's largest ethnic minorities. The jihadist onslaught has deepened the rift among Iraq's Turkmen along sectarian lines, pitting the majority Shiites against the smaller Sunni community.
Tal Afar's Shiites were directly targeted by IS while some members of its Sunni minority joined the jihadists and went on to form a contingent with a particularly brutal reputation in the jihadist organisation's Mosul-based leadership.
Regional focus While federal counter-terrorism, army and police forces, as well as Kurdish peshmerga fighters, are focusing their efforts on Mosul, the Hashed al-Shaabi are now marching on Tal Afar.
Their declared goal is to retake the town and cut off supply lines between Mosul and Syria.
Tal Afar has become a focal point for the regional struggle for influence that is taking place behind the scenes as the Mosul battle unfolds.
The most powerful militias in the Hashed, which is nominally under the command of the prime minister, are forces that answer directly to Iran.
Iran, the region's main Shiite power, and Turkey, which shares a Turkic heritage with the Turkmen, have been vying for influence in Iraq, and both see Tal Afar as a natural target.
Observers have predicted that a Hashed push on Tal Afar could draw Turkey, which has military bases in northern Iraq but has played a limited role in the two-week-old offensive on Mosul, deeper into the battle.