The mountains have emerged where the tectonic plates meet. The collision of the tectonic plates can disrupt the earth causing earthquakes as well as the growth of a mountain. These mountains take awhile to become the giants they are.
Answer:
Việt Nam có 58 tỉnh và 5 thành phố trọng điểm là Hà Nội, Thành phố Hồ Chí Minh, Cần Thơ, Đà Nẵng và Hải Phòng.
I would say that the Rocky Mts were the youngest of all these mountain ranges as they were created between 80-55 million years ago during the Laramide Orogeny and also they are generally much taller than the other mountain ranges mentioned here which is a characteristic of young mountain ranges and their features are sharper as they haven't been eroded the way most of these others have so have been subject to erosion for less time than the others.