Kayan

A distinctive tribal feature of the Kayan Lahwi are brass rings worn by women.

An excerpt from the article 12 facts about Kayan
They are put on girls’ necks around the age of five, and their length increases as they grow. While it may seem like it lengthens the neck, it actually lowers the collarbones and compresses the chest. The length of the neck remains unchanged, but the optical illusion means that women from this tribe are often referred to as "women with a giraffe's neck".