The term you're referring to is likely "Sahel." The Sahel is a semi-arid region that serves as a transitional zone between the Sahara Desert to the north and the more tropical savannas to the south. It is characterized by a strip of dry grassland and is known for its unique environmental and ecological significance.
The "savanna" typically refers to grassland ecosystems found in tropical and subtropical regions, while "stream" refers to a body of water. In this context, the Sahel is the most appropriate term to describe the area between the Sahara and the equator.