Charles Ellicott Commentary 1 Kings 8:1

"Then Solomon assembled the elders of Israel, and all the heads of the tribes, the princes of the fathers` [houses] of the children of Israel, unto king Solomon in Jerusalem, to bring up the ark of the covenant of Jehovah out of the city of David, which is Zion." — 1 Kings 8:1 (ASV)

The elders. —If in this description—found also in 2 Chronicles 5:2, and taken, no doubt, from the original document—the elders of Israel, are to be distinguished from the heads of the tribes, and not (as in the Septuagint) identified with them, the former expression probably refers to the chiefs of official rank, such as the princes and the counsellors of the king, and the latter to the feudal chiefs of the great families of the various tribes.

These alone were specially summoned; but as the Dedication festival (being deferred for nearly a year after the completion of the Temple) was blended with the Feast of Tabernacles, all the men of Israel naturally "assembled at Jerusalem" without special summons.