The phrase "historical conundrum" refers to a perplexing problem or puzzle related to history. There are several synonyms that can be used in place of this phrase depending on the context. Some of the possible alternatives to historical conundrum include "historical enigma," "historical puzzle," "historical mystery," "historical anomaly," "historical paradox," or "historical dilemma." Each of these words has a slightly different connotation, but they all refer to a complex issue or question that requires careful consideration or investigation to understand. In history, there are often debates and disagreements about specific events or interpretations, which can lead to various historical conundrums that require resolution.