The reason why "Gragn" Ahmed pushed "Abyssinians" is due because they were expansionist and Muslim Habeshas from central Ethiopia like Harari, Shewa, Ifat, Wollo etc... were being pushed by Nilotic/Bantu and admixed Oromo expansionist in the south and Christians from the North/east. Yes, Sultanate was somewhat an extension of Ottoman/Arab empires, but "Gragn" Ahmed was combating the expansionist severely omotic admixed Oromos and Christian monarchy.