Sumerian is not a semitic language.
Sumerian is the language of ancient Sumer. It is believed to be a language isolate and to have been spoken in ancient Mesopotamia (modern-day Iraq).
It was attested from c. 3000 BC. Effectively extinct from about 2000–1800 BC. It is used as classical language until about 100 AD.
The language family is 'Language isolate'. The writing system of Sumerian is Sumero-Akkadian cuneiform.