The Sultanate of Arababni (also known as Arbabni or Arabini) was a small Gurage Islamic sultanate located in what is now the Arsi Zone of Ethiopia. Founded around the 12th century, it was the smallest and weakest of the Muslim kingdoms described by the Islamic geographers al-Umari and al-Makrizi.
Sultanate of Arababni Wikipedia
Fetegar (and thus, Arbabni) is the region southeast of the modern capital Addis Ababa, essentially corresponding to the modern Arsi Zone. The Oromo migrations led to the region being renamed for the third time to Arsi, after the Arsi Oromo.
The Fetegar region, being one of the former independent Muslim states in the region, was a primary target of the jihad of Ahmad ibn Ibrahim al-Ghazi (Ahmed Gurey), Imam of the Adal Sultanate.
During the reign of Emperor Amda Seyon I, Arbabni was conquered and annexed by Abyssinia and would become the Fetegar province. Fetegar was occupied by Arsi Oromo during the Oromo migrations and would become part of Arsi Province, and what is now Arsi Zone.