The orcs don’t fare well at the end of The Lord of the Rings. Their armies shattered with the fall of their master Sauron. Aragorn became king of Gondor, prompting resurgent humanity as the power to push what was left of them into the shadows forever. Peter Jackson’s celebrated movie adaptation actually depicts the ground opening up and swallowing them, though a reasonable number escape to parts unknown.

Naturally, the orcs’ ultimate fate matters less than that of Frodo and his companions, and the movies don’t waste any further time retailing what happened afterward. However, author J. R. R. Tolkien kept fastidious notes about every corner of his groundbreaking fantasy world, and they deliver some clues as to the orcs’ collective fate at the dawning of Middle-earth’s Fourth Age.

Certainly, the destruction of Sauron didn’t result in the death of all the orcs. The movie version of The Lord of the Rings: The Return of the King makes a point of showing some still alive as they flee the Black Gates in terror. Tolkien’s Appendix to The Return of the King goes into further detail, covering the War of the Ring in other parts of Middle-earth and the presumed fate of the orcs there. Sauron’s northern army lay siege to the dwarves in the Lonely Mountain, only to flee to the east when they received word of Mordor’s fall. Survival, at least initially, is assured.

From there, firm answers grow hazy, and Tolkien doesn’t mention them in the Fourth Age. Presumably, those who escaped formed rough tribes or raiding parties and survived for a time by hiding in caves, forests and the abandoned places of the world. The goblins of the Misty Mountains presumably survived as well, and their tunnels could support a great number of orcs for some time.

Longevity and questions of age eventually arise. Some sources suggest that orcs are short-lived, yet Tolkien’s timeline puts one of their number — Bolg — at well over a century old. The Silmarillion states that they were created in mockery of the elves, which Jackson’s movie spells out, suggesting a longer age for orc who aren’t killed in battle. Yet females and young are never seen, which presents a huge long-term survival problem. Sauron and similar figures like Saruman could presumably create more, but the species would be doomed without such dark overlords.

Yet Tolkien leaves the door open for their survival, notably with reference to orcs breeding with human beings. The Uruk-hai, or “black orcs,” appear to be hybrids between orcs and humans, and both Tolkien and Jackson mention the two species cross-breeding. If that’s the case, then orcs might have survived in some form or another and endured well into the Fourth Age.

In his novel The Hobbit, Tolkien suggests that hobbits never left the world. They just decided to avoid “ the big folk” and now are seldom seen. A similar explanation might exist for the orcs: fading into the lost and lonely parts of the world until they became something akin to fairy tale monsters. They ceased to be a power in Middle-earth after Sauron, but their copious strength and ability to survive makes full-bore extinction unlikely in Tolkien’s world.