波里斯·雅可弗列维奇·符拉基米尔卓夫提到过阐明辞源和确定词汇的准确涵义在蒙古学中的重要性。他指出,对于研究蒙古社会制度,“‘事实的资料’常常起着较小的作用……尤为重要的是一些零星的细节和闲谈……它们相当大量地散见于草原作家们之中”,而且“这些材料往往必须经过词汇分析才能发现”。“蒙古社会制度”一书中十分珍贵的资料,符拉基米尔卓夫正是在词汇分析的基础上获得的。确定其词源,对于研究蒙古社会制度有着重大意义的词汇之一就是“翁古·孛斡勒”。此词已不止一次引起过研究者们的注意,但是,后面还要谈到,所有论述过这个词的作者,都给了它以十分复杂而又不够明确的阐释。并且,必须注意,他们用了另一个词,即“兀纳罕·孛斡勒”来代替“翁古·孛斡勒”这个词。据某些作者的意见,“兀纳罕·孛斡勒”所表明的似乎是十三至十四世纪的蒙古存在过的一种独特的封建依附形态。兹引各个作者对“兀纳罕·孛斡勒”一词所作的阐释如下: Boris Jackovich Vladimirov mentioned the importance of clarifying the source of the word and of defining the exact meaning of the word in Mongolian. He pointed out that “for the study of the Mongolian social system,” the “factual data” often plays a minor role ... and of particular importance are sporadic details and chatting ... which are scattered among a large number of grassland writers “and ”These materials often have to be lexical analysis to find out.“ Vladivitz, the very material in the book ”The Social System in Mongolia,“ was obtained on the basis of lexical analysis. To determine its etymology, one of the words of great significance for the study of Mongolian social system is ”Wengu Beileuole.“ This term has drawn the attention of researchers more than once, but it goes without saying that all authors who have addressed this term have given it a very complicated but not clear explanation. And, it must be noted that they used the other word, ”Urnhan Beilehler,“ in place of the word ”Wugu Beilehler.“ According to some authors’ opinion, the phrase ”Urnhan Beolle“ appears to be a unique form of feudal attachment that existed in Mongolia during the thirteenth to fourteenth centuries. It is hereby cited that the author’s interpretation of the term ”Wu Nahan Bei Tuo Le" is as follows: