(there may be something about the history of the Great Valley in some of the movies I didn't see yet, so forgive me for any errors.)
"Well, I heard much about this Valley since when we were very young ourselves," Grandpa began. "It was said that our families left long ago to explore the rest of the world. But soon, the world itself began to change. Green food and fresh water were quickly becoming harder to find. And many sharpteeth threaten our livelyhoods day after day. It wasn't until some time ago our herds decide to return to the only place that would have an endless supply of food and safety...the Great Valley.
"For many cold times, we traveled in the direction of the Great Valley. Our herds continued to dwindle. Grandma, Littlefoot, and I are the last of our herd when we finally came here, for instance. But many of our herds managed to make it to the Valley, and saw the imense beauty of this place, even more beautiful than what our grandparents told us about. Soon, many more herds began to join us, and our herds grew.
"Even though we are kept safe from sharpteeth most of the time, we still end up having to deal with some outside the Valley and the few that managed to get in. And we even have to face hardships at affected the Great Valley itself. Once, the Thundering Falls that gives all the water for us and the green food stopped flowing, due to a flying rock that blocked up the water in the Mysterious Beyond. We also had to leave the Great Valley itself for a time because a great swarm of leaf-gobblers destroyed all of the green food. Then we faced some rather...unusual chain of misfortunes that came to the Valley not too long ago. And we finally had to face a very cold time (I did not see LBT 8, so I what truly happened there).
"But even through all of what we faced, the Great Valley always remained as beautiful as it had been for many generations, and it will always remain that way for many more generations."