I don't know where u heard that from, but more than 1/3 of Makhirians live in the mountains especially during the dry seasons. almost all the people in Laasqoray or coastal cities in Maakhir migrate to the mountains during the dry season. there are over 25 villages in Almadow. all the farms of Maakhir are located in the mountain and its surroundings, the only reason why there isn't large cities in the mountains is mainly due to the lack of infrastructure( roads, bridges, etc).
Yeah there aint bridges and roads. Biggest obtacle Maakhirians face. They will overcome it with the right effort.
Aadan Siciid, the biggest sub-clan of CUMAR, after Garaad Cabdalle, entirely dwell on the mountains while some of them also live in Badhan.
Waa niman reer Buureed ah. Waxa kaloo dega, Jibriil Siciidka, Reer Faatax Garaad, yo Nuux Cumarka.
Around Sool area, there is where you find Camel-herding Warsangeli: Reer Saalax, Reer Mohamed(Dubeys), Bahogeyslabe, Bihidoor, Aadan Yacquub, Muxumad, Reer Xaaji.
Particularly, Ugaadhyahan of Dubeys have the largest camel in northeastern Somalia. They don't know nothing of the mountains.
besides aden saciid there is other big tribes that live there as well, such as Husein Isse, Warlabe, nux cumar, some reer garaad, when you go really far east of the mountain you will see a lot of reer haaji and Dubeiys as well.