They weren't fully exterminated, but a great many of them did die. Upon Sauron's defeat, many of his forces immediately surrendered, though this was mostly the men out of Harad or Easterlings. The Orcs mostly fled, and a lot of them died in the chaos of their retreat.
The final installment of the film trilogy shows the Orcs either escaping or being swallowed up by the ground beneath them after the war ends. Since their will was not bound to Sauron now, it is more likely that they ran away in terror and scattered across Middle-earth.
There was a Dark Lord before Sauron was in the picture. Morgoth (also known as Melkor) was the first Dark Lord, and he is the one who first bred the Orcs. Mordor Orcs refer to the Orcs that Sauron bred for his own army. The first Dark Lord Melkor took hostage some Elves from Cuiviénen.
The Fourth Age began once Sauron was vanquished and the One Ring destroyed. The Shire and the kingdoms of Arnor and Gondor were restored. It marked the ascent of Men and the final diminishing of the Elves. Gandalf, Elrond, Galadriel, Bilbo and Frodo sailed for the Undying Lands, as had most Elves on Middle-earth.
Orcs occupied Moria, while the Balrog haunted its depths. The Orc-chieftain Azog became the master of Moria. Thrór, the heir of the Dwarf-kings of Khazad-dûm, attempted to enter his people's ancestral home, and was killed by Azog.
What Happened to Orcs After Sauron's Fall | The Lord of the Rings | Middle Earth
Why was Gandalf afraid of Balrog?
The Balrog, like Gandalf, is a Maia. There is a very real possibility that Gandalf will die in this confrontation. As an istar Gandalf is an incarnated maia, and thus subject to all the frailties and fears that Elves and Men are subject to.
The Orcs of the Mountains though permanently depleted, reclaimed Moria though returning to the service of the Dark Lord Sauron. Sauron's turncoat servant, the fallen Wizard Saruman also stirred up the Orcs tribes in the Mountains, gathering some of the forces he used against the kingdom of Rohan from there.
After the defeat of Sauron in the War of the Last Alliance, Mordor was taken under the control of Gondor, and the Gondorians built fortifications around it to prevent the return of evil things.
Eventually, Morgoth was bound in chains by the Valar and thrown into the Void, leaving the permanent damage his evils had done, and his former lieutenant Sauron, to trouble the world. One day, according to a prophecy, Morgoth will rise again in great wrath, but he will be destroyed in the Dagor Dagorath.
When Halbrand and Galadriel captured Adar, Adar seemed not to recognize Halbrand as Sauron. Adar also claimed to have killed Sauron after watching Sauron experiment on the orcs, whom Adar sees as his children. It's possible Adar was pretending not to recognize Sauron as part of a ruse.
Unlike Dwarves and Hobbits, Orcs wouldn't be bred with any sort of awesome-looking spiky Orcish Marriage Ring. Instead, the breeding process would be closer to breeding animals. Man-flesh would have to be fed to both an Orc and an Orc woman nearby, and they'd both initiate the process.
It was believed by the Eldar that before Oromë first discovered Cuiviénen, Morgoth had kidnapped some of the Avari and cruelly deformed them, twisting them into the first Orcs.
Especially in Tolkien's The Lord of the Rings, orcs appear as a brutish, aggressive, ugly, and malevolent race of monsters, contrasting with the benevolent Elves. They are a corrupted race of elves, either bred that way by the Dark Lord Morgoth, or turned savage in that manner, according to the Silmarillion.
Morgoth, the first to reign terror upon Middle-earth, was more powerful than Sauron and commanded an army of dragons and Balrogs. While both Morgoth and Sauron were cunning, Morgoth's rule and terror lasted longer and his corruption spread further, making him more formidable in the Lord of the Rings universe.
Envy: He hates how he cannot make life and is jealous of Eru's ability to create life which is why he creates Discord and is the prime motivation of Morgoth. If it isn't mine, then I will destroy it. Gluttony: He breaks his promise and betrays Ungoliant, so he can keep the Silmarils for himself.
6 Gandalf. As previously stated, Gandalf is a Maia and is therefore superior to Elves regarding power. Still, this isn't to say that an elf couldn't develop enough skill and power to defeat a Maia. As a bearer of one of the Three Elven Rings (Nenya), Galadriel would have an edge against Maiar like Saruman and Radagast.
Gandalf, known temporarily as the Grey and later the White, and originally named Olórin (Quenya), was an Istar (Wizard), dispatched to Middle-earth in the Third Age to combat the threat of Sauron.
It is said in *Of The Rings of Power and the Third Age* that Sauron did the bare minimum to avoid punishment after the War of Wrath: “When Thangorodrim was broken and Morgoth overthrown, Sauron put on his fair hue again and did obeisance to Eonwe, the herald of Manwe, and abjured all his evil deeds.
Gimli didn't know about Moria's fate because there had been no communication between Erebor and Moria for 25 years, and the Dwarves were hopeful and did not want to accept failure until there was certain news.
According to one theory (via Stack Exchange), Gimli did not know about the fall of Moria in The Lord of the Rings: The Fellowship of the Ring movie due, effectively, to poor communication.
What happened to all the Orcs after the ring was destroyed?
Upon Sauron's defeat, many of his forces immediately surrendered, though this was mostly the men out of Harad or Easterlings. The Orcs mostly fled, and a lot of them died in the chaos of their retreat.
