西燕政權結構、戰略目標與其興衰關係──以立國初期（西元三八四～三八六）為研究中心

The Political Structure, Strategic Aims, and the Relations between the Rise and Decline of the Xi-yan 西燕 Regime: From the Perspective of Its Early Years since Its Establishment, 384-386 A.D

西燕為五胡十六國時期華北諸政權之一，其立國初期由慕容泓、沖兄弟藉淝水戰後前秦出現統治危機時，起事於河東、平陽一帶以復國，並直搗前秦核心區關中，與苻堅數戰，頗多勝績，極居復國優勢。然何以喪失此機，反而不過十年國祚而速亡？實耐人尋味。本文擬對西燕立國之初之政權結構、國家戰略目標、社會背景之關係，探討其立國基礎不穩定之因。其中關於慕容泓起事地點，史料為「關東」，本文將詳細考證其乃「河東」之誤。西燕初期國家戰略目標以西進關中，營救前燕幽帝暐及滯關中鮮卑族為主，本文稱為「西進時期」。後沖殺泓自立，持續此政策，但因在關中殺戮過當不得人心等因素，為西燕其他系勢力所殺，這些勢力傾向東歸前燕立國之關東故地，國策改向東歸，本文稱為「東歸時期」。但此時卻政變頻仍，為何如此？本文亦將討論其因素，其中滯關中鮮卑人有三十餘萬是一因也，此為龐大的現實既得利益，主張東歸之各系勢力為搶奪此一數量龐大、卻可能未有縱系社會組織之散眾，反而對為數已不到十萬之西燕軍團之權力結構，有一定程度之衝擊，這也是「東歸時期」各系勢力爭權傾軋，最後為疏房支之慕容永獲得最終大權之因素之一。本文時間段限以「西進」、「東歸」兩時期約兩、三年間為主。以上各面向內部矛盾，正是西燕不得在關中成功復國之因。至於慕容永定都上黨長子後之史，則暫不論。

The Xi-yan 西燕 was one of the warrior powers during the Shiliuguo 十 六國 period . They had tried to restore the dynasty of Qian-yan 前燕 and had successfully conquered Qian-qin 前秦 , captured its capital , Chang-an 長安 , and almost captured its emperor Fu-jian 苻堅 . However , the Xi-yan 西燕 Still failed and decline ten years later . This research is merely trying to analyze the reason why it declined so fast , why it turned out to be disorder , and examine the relations between its political and social structure which doomed the destiny of Xi-yan.