context: Roughly 70% of the area in the RSFSR consisted of broad plains, with mountainous tundra regions mainly concentrated in the east. The area is rich in mineral resources, including petroleum, natural gas, and iron ore.
question: ఆర్. ఎస్. ఎఫ్. ఎస్. ఆర్. లో ఏ భాగంలో ప్రధానంగా తుండ్రా ఉనికిలో ఉంది?
answers: the east