The collapse of global empires and the shaking of world power structures will ultimately come about through a mix of divine intervention and internal conflict. God will take vengeance by removing mighty kings from their thrones, leading to the total destruction of their realms [מצודת דוד, מצודת ציון, ביאור שטיינזלץ]. This process of dismantling nations follows a specific order: it begins at the very top by striking the government leadership, and then trickles down to wipe out the military forces, fortified cities, and armies, ending in complete loss [מלבי״ם]. Those who are defeated will fall directly into the depths of the underworld [מצודת דוד].
When considering exactly when these massive global shifts take place, commentators offer two main perspectives. One approach views these events through a historical lens, placing them close to the time of the prophet himself. During the eras of Zerubbabel and the kings Darius and Artaxerxes, numerous wars shook the region, even though the ancient records documenting these battles have been lost to time [אבן עזרא]. More specifically, this points to the eventual collapse of the Persian Empire. Although Persia ruled the entire known world at that time, it was destined to fall to a rival kingdom just thirty-four years after the building of the Temple [רש״י].
On the other hand, a second approach understands these events as a vision of the distant future, specifically pointing to the apocalyptic war of Gog and Magog. In this scenario, the destruction will not come from a foreign conqueror, but from within. God will throw the nations into such intense panic and chaos that they will turn their weapons against one another. Armies will wipe each other out, fulfilling the ancient prophecies that men will fall by the swords of their own brothers [מצודת דוד, מלבי״ם].