句子求理解

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The 19 century was the time that saw what we called: Realism developing in the European theater. Um… to understand this though, we first need to look at an earlier form of drama known as the well-made play, which basically was a pattern for constructing plays, plays that the beginning with some early 19 century comedies in France proved very successful commercially.  

请问这句粗体标识的句子是定语从句还是什么从句？ the beginning ... in France 在句子里作什么成分？

谢谢大侠