Why are Scandinavian countries called Scandinavian?

The word "Scandinavia" is derived from the name of the ancient Germanic tribe known as the Scandians. The Scandians were a group of people who lived in the region of present-day Scandinavia during the Iron Age. The name "Scandia" is thought to be derived from the Proto-Germanic word *skand- (which means "to cut" or "to divide"), and it is believed that the name was originally used to refer to the narrow strait between the Scandinavian Peninsula and the Jutland Peninsula. The term "Scandinavia" was later used to refer to the entire region of present-day Scandinavia, which includes the countries of Denmark, Norway, and Sweden.