In the early-to-mid 22nd century, a large organization of criminals had infiltrated the highest levels of the Mazarite government, especially the High Council. The Mazarites decided to ask the Vulcans for help in purging their government of these criminals. The Vulcan High Command sent Ambassador V'Lar, who spent months collecting data on the corrupt government.
In early 2152, she had collected enough evidence against them to prosecute, so the Vulcans sent Enterprise to retrieve her and bring her to Vulcan where she would be safe until she could testify. (ENT: "Fallen Hero")