Where did the Sumerian civilization come from? You would think scholars, academics, and historians have been struggling to solve this cultural riddle, yet we still have hundreds of thousands of Sumerian clay writings crumbling to dust in museums rather than getting them all translated. The Sumerians were a multi-ethnic civilization, including the people who lived in Sumer and other people brought in from outside. The early Sumerian civilization builders came from the Zagros Mountains of western Iran and migrated south into what is now known as Iraq. This we know for sure. They comprise two groups, The Anunnaki Rulers, later called gods and deified, and Sumerian peoples, or indigenous people of the earth. Several Semitic peoples settled in Sumer, according to ancient historical records, starting around 4500 BCE. These immigrants settled throughout Mesopotamia and intermarried with the local population. Over time, these groups created their own cultures and languages but still followed many of the customs of their Anunnaki overlords.