The Great Valley is said to be the most beautiful and perfect place in all the dinosaur world. Littlefoot's reaching it is the goal of the first film and it has been his home and the home of his friends ever since. According to dinosaur legend, the Valley is said to have an unlimited supply of food and to be completely safe from predation by Sharptooth. With how the first film closes with the narrator stating that Littlefoot's descendants would live in the Great Valley for generations "each passing on to the next the tale of their ancestors journey to the Valley, long ago," it can be assumed that the Great Valley dinosaurs would be safe and happy for centuries to come.
In the first film, the Land is said to be changing and the dinosaurs endure drought and famine, as well as increased predation. (The geologic and ecological upheavals are mentioned in later films such as the Great Earthshake. Another example is how Ali's herd's matriarch remembers that her home too suffered due to the Land changing--in her case, flooding.) The leaves upon which they feed dying, some herbivorous dinosaurs travel westwards past the Great Rock that looks like a Longneck and past the The Mountains That Burn in search of the Great Valley. It is a march of many dangers with sharpteeth stalking the herds; many, such as Littlefoot's Mother, Topps's wife and perhaps Pterano's followers. Even so the dinosaurs go on because it, according to legend, is "still lush and green. It was a journey towards life."
Littlefoot and his friends and their families find the Valley at the end of the first film and have lived there ever since. The Great Valley is shown to be surrounded by high walls that keep out nearly all predators and that watching over the Valley is a rock formation the looks like a longneck, Saurus Rock. It should not be confused with the Great Rock that looks like a Longneck that serves as a guide to the Valley. The Valley has waterfalls and a wide system of freshwater. It also has a lot of volcanic activity (volcanoes and geysers) though the lava does not flow into as a ravine separates the volcanos and a few tar pits. For the most part it lives up to its legendary reputation with a plentiful supply of food for all the dinosaurs and lack of predators. Yet while, the Great Valley is far safer than the outside world, it has a degree of incursions for a saurian paradise. Such things range from the rare Sharptooth attack (film II, flim IX, film XI, TV Series), to drought and fire (film III, film VI), diseased individuals (film IV), Swarming Leaf Gobblers (locusts) eating all the food (film V), hurricanes (film VI), scheming villains (film VII), blizzards (VIII), and flooding (film IX). Even so, plants that were lost during disasters quickly grew back and the dinosaurs of the Great Valley do consider themselves fortunate to have a steady supply of food and almost no attacks by predators. Grandpa Longneck says in film II, "The Valley is a wonderful place to grow up."
It is seen that many of the dinosaurs currently in the Great Valley belong to the combined herds that traveled together after the Great Earthshake. That raises the question of whether or not the Valley was empty when the combined herds reached it. This is suggested by how, in The Mysterious Island, Grandpa Longneck speaks to the herds telling them that they'd all lived outside the Valley before. However the dinosaurs he speaks to are far from the entire population of the Great Valley, and in the very next film, The Secret of Saurus Rock, Grandpa Longneck tells the children stories of how the first herds went to the Valley long ago. It should be noted that his wife, Grandma Longneck, promptly chides him for telling nothing but nonsense. Mr. Thicknose, one of the older dinosaurs of the Great Valley, explains to the children far into the eighth film, that he had lived in the Great Valley all his life.
While the dinosaurs in the Valley live there, they sometimes encounter visitors to the Valley who stay for a short while before moving on such as Ali's herd, Doc, or Tippy's herd. The fact that these visitors do not settle in the Great Valley suggests that the dying of the leaves has ended and that is shown in how films after the original Land Before Time show plants outside of the Great Valley to be green and healthy.
West to southwest of the Great Valley is a location only known as the Mysterious Beyond and brief glimpses of it show it to be desolate and inhabited by Sharpteeth and Fast Biters, like Red Claw and his two henchmen Screech & Thud. The Mysterious Beyond as a region surrounds much of the Great Valley. It is unknown what factors prevent overpopulation in the Valley with its lack of predators; it is possible that Great Valley dinosaurs only have few children.
The "Mountains That Burn" refer to a volcanic mountain range southeast of the Great Valley. It was presented as being a place of death, complete with fire and brimstone, and bleached bones. There were tar pits (one of which Petrie fell into) and murdering dinosaurs scattered through it. They are not to be mistaken with the "Smoking Mountains" in the east, which appear in The Stone of Cold Fire, Journey to Big Water, and The Great Longneck Migration. They can be seen from the Great Valley and somewhere at the "Big Water" (ocean). They are depicted as a dangerous and forbidden place, similar to the swamp filled with carcasses and skeletons, shown in The Great Valley Adventure and The Time of the Great Giving.Although Sharpteeth are not allowed in the Great Valley, the herds have allowed Chomper and Ruby to live in the Secret Caverns, as they wish to learn how different dinosaurs can work together. This makes Chomper the only known Sharptooth (though with the exception of Flying and Tiny Sharpteeth) living in the Great Valley.
One popular theory holds that the location of the Great Valley is in Northeast Utah, in a place now known as Ashley Valley.
There are many species of dinosaurs and other creatures that live in the Great Valley. They consist of the following:
- Apatosaurus: Grandma and Grandpa Longneck, Littlefoot, Pat, etc.
- Nodosaurus: Nod
- Hypsilophodon: Hyp's Father, Hyp.
- Muttaburrasaurus: Mutt's Father, Mutt.
- Microceratus: Great Hideous Beast.
- Apatosaurus: Ali's Mother, Ali, Bron, Far Walkers, Old One, Rhett, Saro, etc.
- Brachiosaurus: Shorty.
- Diplodocus: Dara, Doc.
Egg Stealers/Dino Kidnappers