I agree that Amharic is not the "mother tongue." It became prevalent after the fall of Gondar in the 16th century
Ge'ez is not the original either. Ge'ez is a Semitic-Hamitic language that is believed to have originated from the red sea area thru what they call Eritrea today.
The original language is lost to the world because the original language would have been oral and not written.
Oral and written language/communication did not develop at the same speed.
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