"To the east the Somalis were once more on the move. After 1850 one of the Darod Somali groups, the Marehan crossed the Juba river in force. In 1865 they went on to break the Tana Galla and by 1880 had turned on the Boran. Pagan peoples in this region were now being dominated by Muslims, and peasants by nomads from the north."
Source: The New Encyclopaedia Britannica Issue 1974
"The Rer Hassan are the orginal inhabitants. The Isak are further divided into four sections, three of which are called Galti which means strangers, they having come into the country from the north-east during the last six or seven years, in some cases having been with the Mad Mullah. They are typical fighting Somalis and the majority of them have horses and rifles. Numbers of course are very difficult to obtain and are quite unreliable, but probably the Rer Hassan could put 4000 men into the field and the Galti about 9000, of whom the Rer Farah Ugas numbered nearly half."
Source: Great Britain Army Chronicles
And to think that this is just Marehan, not including Ogaden. Southern Darood.