Amhara as per say do not really claim to be children of Israel for ancestry reasons. It is a system by the elite and church establishment.
No Amhara will jump up and down and say his father was from Israel.
Amhara do not talk about ethnicity or parental roots. They only know Ethiopia and Ethiopia only but their Ethiopia is almost the entire Africa.
The Habesha identity was not ancestry either. It was more like a national state like Roman. You can't say all Romans had common ancestry or father.
Some Highlanders only know that identity and for them stick to that.
My Amhara friends for instance laugh when they see the "Amhara regional" flag. Almost all of them do not even know it exists. They have religion identities but not ethnicity.
These friends of mine are mostly Muslim Amhara many of them from Gondar. They tell me how they great grandfathers used to be harassed and asked to convert. There was only Amhara (Christian) and Muslim identity with them.
Even Christian Oromo were just Amhara or same as the rest of the Abyssinians in their eyes.
These brothers laugh their heads off every time we talk about ethnics.
Anyways it's true from religious perspective Amhara adopted a foreign belief where Israelites were idolized and Somalis turned to Arabs for spiritual guidance.
So in both cases it was never about parental, modern generations misunderstood, it was all to do with religion. If you were Muslim it was synonymous with Arab and being Tewahedo was synonymous with Amhara.
Somalis then adopted the identity "Somali Mohamed" once they converted. There were no tribes. The tribes were created much much later and then that's when fake historians and manipulators inserted all these fake Isaaq, Darod, Hawiye identities.
They never really existed no matter how hard to believe. We existed before these guys as people living and walking the Horn among the Oromo, Afar, Amhara, Beja and others.
Northern Ethiopians/Eritreans adopted the Christian Orthodox through Egyptian monks. They were the ones installed the whole system. Even the kebra nagast was originally in Arabic and translated into Geez (also former southern Arab language).
Amhara only appeared in the 12th century.
Somali tribes were formed or established in the same time frame. Maybe a century later.
In conclusion, tribes are myth created by people with big agendas. They probably had past experiences and came from established empires. I suspect they were Arabs in the case of Somalis. They wanted to glorify their culture, faith and civilization. Early Somali converts were hailed as "sons" of "Sheikh X' and the tribes took up those names.
We know those stories failed though because they never knew DNA was going to be invented

Today it's clear all Somalis had common Farah as a father. It's time to embrace it walee. Intan iin ka badan is beyond ceeb.
Personally I believe the entire Horn was one family but some joined the early Christian faith (bulk of this family became Amhara). The rest then migrated either east or south. The Christian sons never suspected the pagan brothers would survive without God and their white man Bible only to return and destroy the little civilization. Conquer for centuries. Then came new white Arab with new religion. Again a section of the family joined from the two camps of Christian and pagans. That new family the bulk would become present Somalis.
The few that make us look different are either religious Jihad migrants, visitors who decided to inter-marry or just foreign guests we had who decided to pregnant our women.
Religion was always a large enterprise. Wherever it went, so did it's salesmen, its enforcers and costumer services. Of course in the case of Islam landing on Somali shores, so did Arabs. The same goes to northern Ethiopia and Eritrea...where Orthodox went so did Greek, Coptic and Armenian priests and their entourage. They often received young girls to enjoy as gift to the Holy ones.
Going back few centuries, we were all in the same hut somewhere in the Horn. Let's face it.
Hararboy,
Don't hate the Oromo. They were good warriors.