I want to know the answer to the following question:
Where did the Northern Xiongnu flee to in AD 91?
All the background I'm provided with is that "After the Northern Xiongnu fled into the Ili River valley in AD 91, the nomadic Xianbei occupied the area from the borders of the Buyeo Kingdom in Manchuria to the Ili River of the Wusun people.". Is that enough to answer the question?
Answer: yes