Charles H. Spurgeon on Psalms 78:9

Many person suppose the passage to refer to the event recorded in 1Ch 7:21-22, where are mentioned the sons of Ephraim, "whom the men of Gath that were born in the land slew, because they came down to take away their cattle. And Ephraim their father mourned many days, and his brethren came to comfort him." The manner of the relation shows that the slaughter must have been great; and this flight and defeat, and their not acknowledging their dependence upon God, it is supposed the psalmist has in view in this place. But the objection to this interpretation is, that the event referred to in the book of Chronicles, evidently occurred at a time anterior to that of the Israelitish exodus from Egypt; whilst Ps 78:11 speaks of these same Ephraimites being forgetful of God's doings and wonderful works which he did at the time of their exit from Egypt. It is, therefore, more probable that Myrka ygk may designate the Israelitish people generally, which Mendelssohn thinks to be the case. He observes that "the meaning of the noun Ephraim was that of a general term for Israel before the reigning of the house of David, because that Joshua the son of Nun, the first judge, was of this tribe; also because the territory assigned to this tribe was in the region of Shiloh: and it is possible that because of the reputation of this tribe in those days, all those who were in high esteem were also called Ephraimites." He might have added another and stronger reason than any of the preceding for this application of the term to Israel, and it is, that Jeroboam, who may be regarded as the founder of the Israelitish monarchy, is said, in 1Ki 11:26, to have been a descendant of Ephraim. The war alluded to may have been one of those which were waged between the ten tribes and the people of Judah. George Phillips.