项羽同刘邦进行的楚汉战争，进入第四年（即自汉元年至汉四年，前206—前203），强弱形势发生了变化，于是在汉四年（前203）九月，有鸿沟分界之事。对此，《史记》、《汉书》有所记载，但不大详细；历来论者不少，基本上是按《史》《汉》所书论析，似乎尚欠深入。我以为，还可 During the fourth year of the war between Xiang Yu and Liu Bang (ie from the first year of Han to the fourth year of Han Dynasty and the first 206 to the first 203 years ago), the situation of strength and weakness changed. Therefore, in the fourth year of Han Dynasty (before 203) in September, Divide the boundaries of things. In this regard, the “Historical Records”, “Han” have been recorded, but not much detail; many historians have basically, according to “history”, “Han” of the book analysis, it seems less in-depth. I think, okay