golden age
noun /ˈɡəʊldən eɪdʒ/
  /ˈɡəʊldən eɪdʒ/
 [usually singular]- golden age (of something) a period during which something is very successful, especially in the past- the golden age of cinema
 Word Originmid 16th cent.: the Greek and Roman poets' name for the first period of history, when it was believed that the human race lived in an ideal state.