Amda-Siyon (1314-1344) was the founder of the powerful Christian empire. His wars were accompanied by carnage and destruction which sent tribes and groups fleeing from the storm centre, abandoning their territory, to seek refuge in difficult areas, where geographic features and distance from the zone of conflict held out hope of asylum. This altered the pattern of ethnic distribution during his reign. There are a number of indications which, beyond a shadow of doubt, establish that some groups, including some Oromo groups, who arrived in the region earlier, were forced to flee from the storm centre. The establishment of a number of Christian military colonies, in Bali, Dawaro, Fatagar, Hadiya, waj and other areas, acted as a powerful dam that checked the flow of pastoral Oromo from the southern region to the central highlands. In the first half of the sixteenth century, the jihad of Imam Ahmad destroyed that dam. With the appalling massacre and destruction on both sides went the fall and destruction of both their defence systems. It is not so much that as so many scholars have presumed, "the so-called Galla invasion" destroyed both countries, as that the two states so battered each other that the way was made clear for surges of advance by the Oromo pastoralists. This happened, fortuitously, at the time when the Oromo perfected their complex gada system, a unique institution, which mobilized them for dynamic warfare and also provided them with a mechanism which enabled them easily and quickly to turn their enemies into allies. This dissertation is an attempt to explain the rapid migration of pastoral Oromo, their settlement in the Gibe region, their formation into states and their Islamization. The five Oromo states of the Gibe region were formed shortly after 1800. Although the existence of these states spanned no more than a few decades, before their annexation by Menelik, the king of Shawa, this brief period was packed with events of crucial importance. It witnessed rapid, agricultural, social, cultural, political, religious and commercial progress, unsurpassed in any of the other Oromo areas in Ethiopia. In the field of religion, the Gibe region became the most famous centre of Islamic learning for all the Oromo of Ethiopia. Even today, along with Dawe in Wallo, the Gibe region is regarded as the best centre of Islamic learning in the Horn of Africa. In the field of commerce, the whirlwind of trading activities in the Gibe region gave birth to an aggressive and dynamic Oromo merchant class, the Africa. In all these states, trading was a highly organized business in which goverment played a key role. This led to the development of an impressive network of institutionized trade, which enabled the Afkala traders to engage in a brisk trade all year round. The caravan routes which crisscrossed the Gibe region and interwove it with the surrounding lands, made the area the major emporium in the whole of southwestern Ethiopia, where the products of the surrounding lands were collected, to be funnelled to the north through Gojjam or to the east through Shawa. The transit trade that entered and left the Gibe region supplied its beneficial effects to the kings in the forms of gifts and customs duties. Indeed, the Gibe states enjoyed prosperity. While the full effect of this prosperity did not reach beyond the land-owning class, the poor peasants in the Gibe region, probably enjoyed a higher standard of living than any peasants in the Ethiopian region. The abundance of cereal crops, supplemented by root crops, guaranteed their safety from famine. Cattle and fowl provided them with milk and meat. The light burden of taxation and the possibility of earning more and buying land also contributed to the better standard of living of the ordinary peasant.