Led by Usma bin Luai, the Tayy invaded the mountains of Ajaa and Salma from Banu Assad and Banu Tamim in northern Arabia in their exodus from Yemen in 115 CE. These mountains were renamed to Jabal Tayy (Tayy's Mountain), and then again in the 14th century, after the tribe changed their name, to Jabal Shammar. There, Tayy, later Shammar, became urbanised city-dwellers in the city of Ha'il, nomadic pastoralists, camel-herders and horse-breeders in northern Najd, or agriculturists in the countryside outside Ha'il or in the surrounding desert oases. These divisions were based on profession, personal interest and skill, and not family or blood-line stratifications within the tribe. It is common for the same nuclear family to have members living each of the three different lifestyles. Because of their strength and blood relations with the Yemenite dynasties that came to rule Syria (Ghassanids) and Iraq (Muntherids), the Tayy expanded north into Iraq all the way to al-Hira, the capital at the time. Oral tradition mentions that the first chiefs of the Shammar tribe, Arar and Omair, were of the 'Abda family of Dhaigham, who ruled Shammar from Jabal Shammar. In the 17th century, a large section of the Shammar left Jabal Shammar under the leadership of the Al Jarba and settled in Iraq, reaching as far as the northern city of Mosul, their current stronghold. The Shammar are currently one of Iraq's largest tribes and are divided into two geographical, as opposed to genealogical, subsections. The northern branch, known as Shammar al-Jarba, is mainly Sunni, while the southern branch, Shammar Toga, converted to Shia Islam around the 19th century after settling in southern Iraq.