Why did the pony leave that beautiful meadow? What happened afterwards? answer

You mean the movie Little Horse King? I saw it a long time ago. I remember that it was because of the persecution and slaughter of local Indians and protozoa by the westward movement of immigrants. The most direct reason is that a white cowboy wants to use a pony as a mount. Pony loves freedom and doesn't want to be captured by others. Finally, he regained his freedom with the help of his Indian friends.