Answer:
Two advances that are important for Sumerian civilizations are development of written letter and development of irrigational system.
Step-by-step explanation:
Sumerian civilization is one of the world's first civilization where first countries and political organization emerged. Created in the valley of Tigris and Euphrates, this civilization developed irrigational system that enabled people to create more permanent settlement in that area and to develop agriculture. On the other side, the development of written letter enabled the creation of certain institutions that enabled easier functioning of the city-states that were created there.