Well, lets be honest and fair about this subject:
During Iman axmed Gurey strugle against sultan Abubakar it is clear the most Somalis tribes were not on his side. except Gerri people, the Marehans and Habar Maqdi were sworn enemies of the imam Axmed and they were clearly sided with Sultaan of Harar However as the imam became victorious the Somalis joined the Jihad,
Harla: which i believe was Afar people wholeheartedly supported Imam Axmed and Sultan of Harla nation was Imam Axmed's maternal uncle so we at least know Axmed mother was not Somali but Harla.
The ancient names of that region which was Adal & Ifat both those names are being retained by Afar people which call themselves Adals and Ifat is Afar region near Awash valley.
Tha core of Adere people is Muslem habasha highlanders or people referred as Jabartis in Ethiopian highland and rest must be self loving Somali-Oromo forks as someone said earlier.
There is no mention Oromo people were among warring parties except Maya which is under Arsi federation today.
I am talking prior to Imam Ahmed's existence!
Harla is not afar. Adere people like to claim they are harla, thus native to hararghe but thats false. They try to say that harla were the ancient muslims of this land but i believe they were non muslim pagans. efforts are being done to try link past cities of old and ancient muslim archeological finding with harlas but i disagree. I believe those the muslim related findings are do the old arab population that existed here which goes with my belief that arabs made harar not the aderes. the old arab population can be linked with the argobas since really the argobas are arabs!
Ar-go-ba really is the name amharas gave them which is really arab-ba. Argoba is like equivalent to mowlad.
Harla could be the precursor of this land and the stock that easterners are represented in. That meaning harlas are evident in somalis(Issa), Afars, and eastern Oromos.
As for adere they are clearly christian axumities that adopted Islam beacause of arabs establishment of harar. And the Maya are also evident that they are also are native haraghe. There are clear manuscripts accounting the maya in harar.