The phrase "was a constituent" can be replaced with a number of synonyms depending on the context. For example, it could be substituted with "was a part of", "comprised", "was an element of", or "constituted". Other possible options include "made up", "formed", "composed", or "belonged to". The choice of synonym will depend on the writer's intention and the specific meaning they wish to convey. Using synonyms can help to add variety and interest to writing, while also helping to clarify meaning and avoid repetition.