He said Ethiopia never was never given land that wasn't historically Ethiopia. Since when was the Ogaden Ethiopian again. Maybe the raids here and there into Muslim lands and the fact that Muslims and Ethiopians fought over Harar. But that's as far inland they got into the East.
Historic Christian Abyssinia was literally only current day habesha territory of Eritrea, Amhara region, and Tigray region and maybe a little into Oromo territory. Everything east of that was controlled by Muslims and their allies.