This article has two purposes: 1) to provide a first historical outline of the Tishana or Me'en, a small 'tribal' group living in southwestern Ethiopia, and 2) to illustrate the importance of a political economy approach for the explanation of such a process. Inspiration has been derived from the historical anthropological approach of E. Wolf (1982), which postulates the interdependence of political economic factors on the one hand, and social dynamics and cultural factors on the other. The vast majority of Me'en speakers now live in highland areas west of the Omo. However, some of the people who currently speak Me'en were pastoralists who lived in the lowlands bordering the southwestern Ethiopian highlands. The problem explained here is how and why a portion of these Me'en pastoralists left the lowlands and how they successfully adapted to highland areas where cattle keeping was notoriously difficult and where the invading northerners tried to prevent them from settling. A further issue is how they were able to absorb other groups and individuals from different ethnic origins. The author argues that the very expansion of the Me'en out of the Omo Valley into the highlands - that is the reshaping of their social reproductive system in a new ecoeconomic niche - was fuelled by Me'en ideology itself, and that this ideology was activated by the confrontation of the Me'en with the expanding frontier of the Abyssinian State. Their cultural ideology, bound up with cattle, entered into the adaptation process of the Me'en groups in a period of crisis. Bibliogr., notes, ref