The Garoghlanian tribe has been mentioned in "The Summer of the White Horse". Does this tribe exists or existed or is it fictitious?

This one is a bit tricky to answer.  I think it is difficult because it addressed a challenging, albeit unaddressed, situation in history.  The Gargoghlanian group of people were Armenians, according to the short story.  We are not sure if they actually did exist.  This is not to say they were invented, but it is only to say that it is challenging to find information about the group's existence.  The reason this is so is because it is entirely plausible that this group did exist, but were one of the many groups of people that were wiped out by the Armenian Genocide that happened in Armenia at the hands of the Turkish government immediately after World War I.  This group of Armenians could have been in existence and then murdered as were many Armenians this holocaust.  The Armenian Genocide is one of the first modern examples of Genocide but is also concealed because of A) Its timing after World War I, when other world events obscured it and B)  The Turkish government does not fully accept its complicity in the genocide and disputes that it actually was a genocide.  The Garoghlanian Armenians seem to find themselves within this historical anomaly.

Saroyan, author of The Summer of the White Horse, is heavily influenced by the Armenians who did settle in California, specifically Fresno, around the time of the Great Depression.  Fresno was seen at the center of the Armenian American population, and given the fact that his stories centered around this group of Armenians, we can assume that Saroyan has some knowledge of the specific group of the Garoghlanians.  It is difficult to pinpoint if this group actually existed in Fresno at the time.  Perhaps, Saroyan invented this group of Armenians, or he had heard about this group from oral traditions passed down from elders.  If we extrapolated this to a wide degree, maybe Saroyan is making a statement about the Armenian genocide, and its lack of acknowledgement, by making the protagonist of his short stories an adolescent of a group of people that were wiped out at the hands of a government.  Essentially, then, we are reading and revelling in the stories of a group of people who speak to us from beyond the grave, cut down in an unspeakable atrocity.  I cannot say that this sect of Armenians is fictitious because to do so, in my mind, moves me closer to denying the Armenian genocide.  We cannot find a record of the group's existence.  I think it can be stated that while we lack a foundational record of the tribe, the stories Saroyan writes is to represent the Armenian community, a group that has been forgotten to some extent in the records of history.