Before then is an expression that refers to a time period that occurred in the past. There are several synonyms that can be used interchangeably with this phrase, including prior to, earlier than, and preceding. Other options include formerly, previously, and antecedently. These words are all related to the concept of something happening before a particular point in time. They can be used to describe events, actions, or things that existed before then. By using different synonyms for before then, it is possible to add variety and nuance to your language and make your writing more engaging.