I use geological concepts of 'points of convergence' and 'subduction zone' for ease of visualization purpose only. Otherwise, the movement remains that of a social or human march or migration for land acquisitions.
Definitions
1. points of convergence is where the two powers meet and live amicably where none is absorbed by another
2. subduction zone is where either Oromo or Amara is more dominant than the other with the possibility of absorbing the other, meaning loss of language, i,e, Gondar and Yeju for Oromo supremacy, and later loss of Gondar and Yeju and the rest of Ethiopia, especially after Tewodros for Amara supremacy.
The northward march of Oromo from Borana toward central Ethiopia, southwest and southeast Ethiopia overran groups that separated Amara from it and came close to confront it in southwest, southeast and central Ethiopia on which it bore some influences on migrants from north Shewa. This is historically accurate. Oromo met Amara in north, central, southeast and southwest Ethiopia, not the vice versa.
will continue......