The Metal Head Wars was a series of conflicts between the Metal Heads (or Hora-Quan) and a number of other factions whose purpose was to protect the Precursor Stone. Eons from the Haven City era, the Precursors "waged a terrible war with the Hora-Quan," who, "driven by their dark leader," were successful in destroying Precursor civilization and "swarmed the universe unopposed, looking for the last relics of [the Precursors'] power." In allegiance with the Precursors, Mar was entrusted to the seemingly last Precursor power, the Precursor Stone.
Metal Kor, the leader of the Metal Heads, was eventually released into Sandover Village through the Rift Gate that was opened by Jak in the beginning of Jak II. As Jak, along with Daxter, Keira Hagai, and Samos Hagai were sent into the future, Metal Kor began scouring the planet for the Precursor Stone. But, "Mar was clever," according to Metal Kor. He hid it well within his tomb, and built an entire city (Haven) shielded by the Shield Wall to protect it. Later, Metal Kor exacted battle against Haven City. After the fall of the House of Mar in Haven, Baron Praxis came to throne, and managed to negotiate a temporary cease war with Metal Kor. He promised to provide the Metal Heads with supplies of eco, so long as they only attacked the city enough to fabricate the illusion of war time, which would justify his placement in leadership over Haven City and maintain the fall of the House of Mar.
However, Metal Kor grew impatient. Baron Praxis, realizing that the deal was unsustainable, began facilitating back up plans with which he planned to destroy the Metal Heads at their nest. Metal Kor was aware of this, and, in a final meeting with the Baron at the Construction Site inside of Haven City, demanded the stone, which the Baron had procured after finding the Tomb of Mar. The Baron refused, to which Metal Kor responded with a fatal blast, and declared he perform a "one brick at a time"-search for the stone inside the city. Praxis had originally planned to use the stone in a Piercer Bomb he was building, but on his death bed, left it up to Jak, stating he was the "supreme warrior." Jak proceeded to take the stone to the Metal Head Nest, and used it to activate Mar's Gun, which Mar built to penetrate the nest, but died before he could use it. Jak was then able to penetrate the nest and killed Metal Kor, effectively putting an end to the Metal Head Wars. The stone was then activated by young Jak, which depleted its worth, as the Precursor entity that lie inside of it had traveled into the Rift Gate to allow an "ancient race [to begin] again."