The strongest nomad unit on the Gulf coast, the Ajman enveloped the Hasa oasis on its north and east in summer and fell back over the Summan plateau toward Sudair in winter, covering at one season or another an area the Admiralty put at not less than 20,000 square miles. Unusually cohesive — its sections shared a single dirah rather than splitting it — and unusually good at federating with weaker neighbours such as the Beni Khalid and Beni Hajar, the tribe was recalcitrant under Ottoman rule in Hasa and then under Ibn Saud, whose paramount chiefs came from the Ibn Hithlain house.
Not an ending: Ibn Saud punished Ajman raiding in 1915 and drove much of the tribe north into Shammar country, their chief submitted to Riyadh at the end of 1915, and the dirah was closed off by the Uqair Protocol of 1922 and the proclamation of the Kingdom of Saudi Arabia in 1932. The Ajman continue in Saudi Arabia, Kuwait, Qatar and the UAE.
Its 'The Ajman' section is the most detailed published description of this tribe's seasonal range, cohesion, alliances and chieftainship (Ibn Hithlain), including the only quantified area figure found for any Arabian dirah. Full text read on the Internet Archive.
The source the Admiralty Handbook itself cites for the Ajman (on the Jiblan section of the Mutayr joining them before 1908); the standard tribe-by-tribe gazetteer of eastern Arabia. Existence verified on Open Library (/works/OL9800557W, ISBN 1852070307).