Theories differed depending on how documents were interpreted but since the majority of them note that Soun was from the Ise clan of Bitchu, this has become an accepted fact.
従来の説は文献の解釈の違いによるところが大きく、さらに「備中伊勢氏」説は史料が最も豊富で多岐にわたる事も出自解明に寄与した。