With the construction of the Temple complete, the time arrived to fulfill its central purpose: bringing the Ark of the Covenant into the Holy of Holies so that the Divine Presence could rest within it [מצודת דוד, אברבנאל]. This monumental step was designed to bridge the heavenly Jerusalem with the earthly one, allowing God to dwell fully within the physical world [אלשיך]. To carry out this event, King Solomon convened a massive public gathering. A large assembly was essential because the Divine Presence rests most completely among a great multitude [צאינה וראינה]. Additionally, Jewish law required the presence of a high court of seventy-one judges to officially sanctify the Temple courtyard [מלבי״ם].
To meet these needs, Solomon gathered the elders of Israel, comprising the judges, sages, and members of the high court [רלב״ג, אברבנאל, מלבי״ם]. Alongside them, he summoned the heads of the tribes and the leaders of the large Israelite families [רש״י, ביאור שטיינזלץ]. While these are presented as distinct groups, some consider these titles to be referring to the exact same set of leaders, repeated simply for clarity [מצודת דוד]. Ultimately, gathering all the national leadership served to bestow immense honor upon the occasion, the king, and the Ark itself [מלבי״ם, אברבנאל].
The ultimate goal of this grand procession was to move the Ark up to Mount Moriah [ביאור שטיינזלץ]. Until this moment, the Ark had been kept in the City of David, where it had remained ever since King David brought it from the house of Oved Edom [רש״י, רד״ק]. Bringing the Ark into the Holy of Holies represented the closing of a historical circle and the fulfillment of King David's greatest ambition. David had long been pained by the fact that the Ark resided in a temporary tent, and he deeply desired to transfer it into a permanent house of honor [אברבנאל].