Around 90% of Muslims in Oman adhere to Ibadi Islam
Ibadism: Origins and Early Development in Oman
Oman: Waking up too - The Economist
Discovering Oman, Ibadi Islam, and the Indian Ocean - Valerie Hoffman
Majority of Tunisian Ibadites live on the Tunisia island Djerba
Ibadites primarily live in the M'zab Valley of Algeria.
Ibadites in the M'zab Valley: Wikipedia
M'zab Valley: Journal of the Royal Anthropological Institute of Great Britain and Ireland
The majority of Libyan Ibadites live in the Nafus Mountains.
During the 19th century Zanzibar attracted Ibadi scholars.
Articulation of Ibadi Identity in Modern Oman and Zanzibar
The Other "Andalus": The Omani Elite in Zanzibar and the Making of an Identity
Ibadism is one of the main sects of Islam along with Sunni and Shi'i Islam. Ibadi Islam emerged around 20-60 years after Prophet Muhammad's death in 632 AD.
Ibadism, a distinct sect of Islam that is neither Sunni nor Shi‘i, exists mainly in Oman, East Africa, the Mzab valley of Algeria, the Nafus mountains of Libya, and the island of Jerba in Tunisia. The sect developed out of the seventh-century Islamic sect known as the Khawarij, and shares with that group the desire to found a righteous Muslim society and the belief that true Muslims are only to be found in their own sect. Ibadis refer to themselves as “the Muslims” or “the people of straightness” (ahl al-istiqama). Nonetheless, Ibadis see themselves as quite different from Khawarij. - Valerie Hoffman, An Introduction
For more information on the History of Ibadi Islam you can look at the UIUC Library Resources as well as the following sources:
Ibadi Islam: An Introduction - Valerie Hoffman
Ahmed Souaiaia: History and Origins
Journal Articles on Ibadi History:
Information on the historical Ibadi Dynasties:
Kitab al-Istiqama - Muhammad ibn Sa'id Kadami
Doctrinal Differences with other denominations: Wikipedia
Ibadi Doctrine and Berber Identity - Mohamad Ballan
Ibn Sallam al-Ibadi - Kitab fihi bad' al-Islam wa shara'i al-din