1) The Appalachian Mountains, running along the eastern coast of the United States, are one of the oldest mountain ranges in the world.

2) The Mongol Empire, under the leadership of Genghis Khan, became the largest contiguous empire in history, spanning from Asia to Europe.

3) Sushi is a traditional Japanese dish made of vinegared rice combined with various ingredients, such as raw or cooked seafood, vegetables, and nori (seaweed). It is known for its artful presentation and delicate flavors, and has gained immense popularity worldwide. Sushi can take many forms, including nigiri (hand-pressed rice topped with ingredients) and maki (rolled sushi wrapped in seaweed), and is often enjoyed with soy sauce, wasabi, and pickled ginger.

4) The coldest known temperature in the universe was achieved in a laboratory in 2019, reaching a fraction of a degree above absolute zero (-273.15 degrees Celsius).