Jews and Joes

The House of Joseph called by the name "Isaak" (Saka)

Genesis 21:12: But Elohim said to Abraham, "Do not be distressed because of the lad and your maid; whatever Sarah tells you, listen to her, forthrough Isaac your descendants shall be named.

Ephraim, from the House of Joseph, was the inheritor of Abraham's birthright promise of multitudes from above. See Two Sticks of Abraham.

In Amos 7:16, יהוה calls the House of Israel by the title "House of Isaac". The context of Amos chapter 7 clearly points to the House of Joseph, not to the House of Judah, since Amos was told to flee to Judah, but to continue to prophecy to Israel (Joseph).

What people became know by the name "Isaac"?

Well, first remember "Isaac" is an English version of a Hebrew name, which was: יצחק pronounced as Yitschâq or Yitsak.

Persia just happened to call a people by the name "Saka". These exact same people were already suspected Israelite descendants from the Northern Kingdom of Joseph because of statements made by Josephus in the 1st Century CE/AD.

See Who are the Saka / Sacae / Scythians?