expression · A figurative reference to a long, tedious, or extremely complicated story or situation.

这件事的来龙去脉说起来就像二十四史那么长，咱们以后再慢慢谈吧。

expression · A collection of twenty-four official Chinese dynastic histories covering the period from roughly 3000 BC to the 17th century.

《二十四史》是中国古代各朝撰写的官修史书的总称。