[42][43] This name theory was especially popular among German historians who once believed that the Oromo were related to the ancient Gallic tribe in France.

[44] Another outdated theory of its origin comes from the belief that the Oromos rejected the offer to convert to Islam by Muhammad as their official religion, thus the prophet giving them the name Qal la or هو قال لا meaning "he said no".

This reference suggests that by the early 14th century, the term was already in use to denote both the people and the region they inhabited, indicating a recognized presence and possibly a distinct socio-political or geographical identity within the historical records of the time.

[54] Saint Tekle Haymanot (1215–1313) is said to have undertaken extensive missionary work, and the Christianization and Proselytization of the Galaan[55] In the hagiography of Sheikh Ishaq Ahmed of Alawi, who arrived in Zeyla in 1153.

He later traveled to Harar and then journeyed among the Arussi, a subgroup of the Oromo people, before eventually settling in Meit, a city small coastal town on the Gulf of Aden.

Sheikh Ishaq played a role in the Islamization of Arsi Oromos, where it has said that 80 clans have converted and adopted Arabic appeals in the 12th century.

Prior to this movement, the Oromos were divided into two major confederations, the Boorana and the Barento, who lived in the west and east of the Rift Valley respectively.

Under Susenyos's successors, many Oromos would continue to rise to positions of prominence in imperial service, and for a period even change the official language of the empire from Amharic to Oromiffa during the rule of the half-Oromo emperor Iyoas I.

Notable rulers such as Ras Mikael of Wollo and the uncrowned emperor of Ethiopia, Lij Iyasu (1913–1916), descend from this ruling family.

According to oral and literary evidence, certain Somali and Oromo clans fought each other throughout the sixteenth, seventeenth and eighteenth centuries, particularly near their eastern borders.

[76] He described them as such: "[The] Galla breed is the most beautiful in Africa; it is not originally from Abyssinia; she came there by invasion, as we will see below in the history that I will give of the Kingdom of Choa (Shewa).

The Gallas are, in general, well built, they have a tall figure, a broad and raised forehead, an aquiline nose, a well-cut mouth, a copper complexion rather than black; their hair is braided into small braids which float around their heads, and mix something graceful with the expressive and noble character of their physiognomy: accustomed, from their most tender youth, to ride horses, to carry the butcher and the spear, they are excellent horsemen and insensitive to the harshest fatigue; full of courage and valor in combat, they showed themselves, in their fields, skillful and laborious farmers: this great nation, because we can call it that could led by an enterprising leader, make itself master of the whole of Africa.

In the areas were the Oromos submitted peacefully, such as the Kingdom of Jimma, the indigenous rulers were made tributaries to the crown but were allowed to self-govern themselves with minimal interference from the central government.

The movement raised the consciousness of the Oromo regarding the significance of their own cultural and historical contributions and their status as a people within the Ethiopian state.

From west to east: the Borana Oromo, also called the Booranaa, are a semi-pastoralist group living in southern Oromia and northern Kenya.

[97] According to a 2016 estimate by James Minahan, about half of the Oromo people are Sunni Muslim, a third are Ethiopian Orthodox, and the rest are mostly Protestants or follow their traditional religious beliefs.

However, according to Terje Østebø and other scholars, this term is a neologism from the late 1990s and its link Oromo ethno-nationalism and Salafi Islamic discourse has been questioned, in their disagreement with Christian Amhara and other ethnic groups.

[113] The Oromo people, depending on their geographical location and historical events, have variously converted to Islam, to Christianity, or remained with their traditional religion (Waaqeffanna).

[116] In the Islamic Kingdom of Jimma, the Oromo society's caste strata predominantly consisted of endogamous, inherited artisanal occupations.

For example, Tumtu were smiths, Fuga were potters, Faqi were tanners and leatherworkers, Semmano were weavers, Gagurtu were beekeepers and honey-makers, and Watta were hunters and foragers.

[127] In December 2009, a 96-page report titled "Human Rights in Ethiopia: Through the Eyes of the Oromo Diaspora", compiled by the Advocates for Human Rights, documented human rights violations against the Oromo in Ethiopia under three successive regimes: the Ethiopian Empire under Haile Selassie, Marxist Derg and the Ethiopian People's Revolutionary Democratic Front (EPRDF), dominated by members of the Tigrayan People's Liberation Front (TPLF) and which was accused to have arrested approximately 20,000 suspected OLF members, to have driven most OLF leadership into exile, and to have effectively neutralized the OLF as a political force in Ethiopia.

[128] According to the Office of the United Nations High Commissioner for Human Rights, the Oromia Support Group (OSG) recorded 594 extrajudicial killings of Oromos by Ethiopian government security forces and 43 disappearances in custody between 2005 and August 2008.

[129] Starting in November 2015, during a wave of mass protests, mainly by Oromos, over the expansion of the municipal boundary of the city of Addis Ababa into Oromia, over 500 people have been killed and many more have been injured, according to human-rights advocates and independent monitors.

[134] Some have blamed the rise in ethnic violence in the Oromia Special Zone Surrounding Finfinne on the Prime Minister Abiy Ahmed for giving space to groups formerly banned by previous Tigrayan-led governments, such as the Oromo Liberation Front and Ginbot 7.

[135] Protests broke out across Ethiopia, chiefly in the Oromia region, following the assassination of musician Hachalu Hundessa on 29 June 2020, leading to the deaths of at least 200 people.

[141] Accordingly, Oromos played major roles in all three main political movements in Ethiopia (centralist, federalist and secessionist) during the 19th and 20th century.

In addition to holding high powers during the centralist government and the monarchy, the Raya Oromos in the Tigray regional state played a major role in the Weyane revolt, challenging Emperor Haile Selassie I 's rule in the 1940s.

In numerous cases, actual or suspected dissenters have been detained without charge or trial, killed by security services during protests, arrests and in detention.

[162] On 12 December 2015, the German broadcaster Deutsche Welle reported violent protests in the Oromo region of Ethiopia in which more than 20 students were killed.

That year Ethiopian security forces responded to peaceful protests by firing tear gas and live bullets at over two million people surrounded by a lake and cliffs.