By about 7000 B.C. at the latest, linguistic evidence indicates that both Cushitic speakers and Omotic speakers were present in Ethiopia. Linguistic d

Ethiopia: Historical Setting
Library of Congress Country Study 
Origins and the Early Periods Ethiopia.

By about 7000 B.C. at the latest, linguistic evidence indicates that both Cushitic speakers and Omotic speakers were present in Ethiopia. 

Early Populations and Neighboring States
Details on the origins of all the peoples that make up the population of highland Ethiopia were still matters for research and debate in the early 1990s. Anthropologists believe that East Africa's Great Rift Valley is the site of humankind's origins. (The valley traverses Ethiopia from southwest to northeast.) In 1974 archaeologists excavating sites in the Awash River valley discovered 3.5-million-year- old fossil skeletons, which they named Australopithecus afarensis. These earliest known hominids stood upright, lived in groups, and had adapted to living in open areas rather than in forests.
Coming forward to the late Stone Age, recent research in historical linguistics--and increasingly in archaeology as well--has begun to clarify the broad outlines of the prehistoric populations of present-day Ethiopia. These populations spoke languages that belong to the Afro-Asiatic super-language family, a group of related languages that includes Omotic, Cushitic, and Semitic, all of which are found in Ethiopia today. Linguists postulate that the original home of the Afro-Asiatic cluster of languages was somewhere in northeastern Africa, possibly in the area between the Nile River and the Red Sea in modern Sudan. From here the major languages of the family gradually dispersed at different times and in different directions--these languages being ancestral to those spoken today in northern and northeastern Africa and far southwestern Asia.
The first language to separate seems to have been Omotic, at a date sometime after 13,000 B.C. Omotic speakers moved southward into the central and southwestern highlands of Ethiopia, followed at some subsequent time by Cushitic speakers, who settled in territories in the northern Horn of Africa, including the northern highlands of Ethiopia. The last language to separate was Semitic, which split from Berber and ancient Egyptian, two other Afro-Asiatic languages, and migrated eastward into far southwestern Asia.
By about 7000 B.C. at the latest, linguistic evidence indicates that both Cushitic speakers and Omotic speakers were present in Ethiopia. Linguistic diversification within each group thereafter gave rise to a large number of new languages. In the case of Cushitic, these include Agew in the central and northern highlands and, in regions to the east and southeast, Saho, Afar, Somali, Sidamo, and Oromo, all spoken by peoples who would play major roles in the subsequent history of the region. Omotic also spawned a large number of languages, Welamo (often called Wolayta) and Gemu-Gofa being among the most widely spoken of them, but Omotic speakers would remain outside the main zone of ethnic interaction in Ethiopia until the late nineteenth century.
Both Cushitic- and Omotic-speaking peoples collected wild grasses and other plants for thousands of years before they eventually domesticated those they most preferred. According to linguistic and limited archaeological analyses, plough agriculture based on grain cultivation was established in the drier, grassier parts of the northern highlands by at least several millennia before the Christian era. Indigenous grasses such as teff1 and eleusine were the initial domesticates; considerably later, barley and wheat were introduced from Southwest Asia. The corresponding domesticate in the better watered and heavily forested southern highlands was ensete, a root crop known locally as false banana. All of these early peoples also kept domesticated animals, including cattle, sheep, goats, and donkeys. Thus, from the late prehistoric period, agricultural patterns of livelihood were established that were to be characteristic of the region through modern times. It was the descendants of these peoples and cultures of the Ethiopian region who at various times and places interacted with successive waves of migrants from across the Red Sea. This interaction began well before the modern era and has continued through contemporary times.
During the first millennium B.C. and possibly even earlier, various Semitic-speaking groups from Southwest Arabia began to cross the Red Sea and settle along the coast and in the nearby highlands. These migrants brought with them their Semitic speech (Sabaean and perhaps others) and script (Old Epigraphic South Arabic) and monumental stone architecture. A fusion of the newcomers with the indigenous inhabitants produced a culture known as pre-Aksumite. The factors that motivated this settlement in the area are not known, but to judge from subsequent history, commercial activity must have figured strongly. The port city of Adulis, near modern-day Mitsiwa, was a major regional entrepôt and probably the main gateway to the interior for new arrivals from Southwest Arabia. Archaeological evidence indicates that by the beginning of the Christian era this pre-Aksumite culture had developed western and eastern regional variants. The former, which included the region of Aksum, was probably the polity or series of polities that became the Aksumite state.

Note
1 Teff is a cereal indigenous to Ethiopia, to which its consumption is almost entirely confined. It is the most widely grown grain in the highlands, where its flour is preferred in the making of the unleavened bread injera, the traditional form of cereal intake.
 
Ethiopia: Historical Setting
Library of Congress Country Study 
Historical Setting <<< Contents >>> The Aksumite State