Researching about Guan Xiu' Going North

To research Guanxiu's life,we must consider whether he went the frontier.The question about whether he went to the north or when he went always puzzles scholars.Although most scholars believe that Guan Xiu have been to north,they basically leave the questions open,or were not even mentioned.The author research that Guan Xiu indeed have been to visited the Northwest,Jibei and other places by his own poems.The time was the sixth year in Xiantong Yi Zong.