They largely lived among the north Arabian mountain ranges of Aja and Salma with Khaybar north of Medina as their most important oasis, and from there they would make incursions into Syria and Iraq during times of drought. Their concentration in Jabal Aja and Jabal Salma lent the mountain ranges their ancient, collective name "Jabal Tayy". Prior to the Tayy migration, the mountains had been the home of the Banu Assad, who lost some territory with the arrival of Tayyid tribesmen. However, the two tribes ultimately became allies in later centuries and intermarried. In ancient times, the two main branches of the Tayy were the Al al-Ghawth and Al Jadila. The tribesmen lived in different parts of the region, with those living among the mountains known as the "al-Jabaliyyun" (the Mountaineers), those on the plain (mostly from Al Jadila) known as "as-Sahiliyyun" (the Plainsmen) and those on the desert sands known as "al-Ramliyyun".