The Shammar took the twin mountains of Jabal Aja and Jabal Salma from the older Tayy and made Jabal Shammar their seat, ranging from the south-eastern Nefud north almost to Najaf. Around 1650 they pushed into the Syrian Desert and broke the Mawali; early in the 19th century the Anizah drove part of the tribe across the Euphrates, splitting it into a southern body under the Rashidi emirs of Ha'il and a politically separate northern body in the Jazira under Ibn Jarba. Their feud with the Anizah dominated the northern desert for 150 years.
Not an ending: the Rashidi emirate at Ha'il fell to Ibn Saud in 1921 and the tribal dirah was absorbed into the Kingdom of Saudi Arabia proclaimed in 1932, while the Jazira Shammar remained on the Iraqi side of the mandate frontier. The confederation persists in both countries today.
The standard scholarly monograph on Shammar tribal politics and the Rashidi shaikhly house at Ha'il — the specific study of this confederation's leadership rather than a general Arabian survey. Existence verified on Open Library (/works/OL4131285W, ISBN 1850433208).
Musil's field survey of Jabal Shammar and the northern Najd steppe, the most detailed topographical description of the Shammar dirah by a trained observer. Existence verified on Open Library (/works/OL5522298W).