Chinese characters are the written symbols of the Chinese language. They constitute the world's oldest living written language system. Many Chinese characters created in ancient times are still in use today. In contrast, other writing systems born around the same period—such as those in ancient Egypt, India, the Tigris-Euphrates Basin, and the Aegean region—are now functionally extinct. Chinese characters were created by the ancestors of the Han ethnic group. With an inherently strict system of structural patterns, these characters have evolved and spread in consistent ways despite huge phonetic variations in pronunciation across different periods and regions.