Cal. Rev. & Tax. Code § 16881

In the case of a transferor who was not a resident of this state at the date of any generation skipping transfer made by him, the superior court of the county in which any of the transferor’s real property is situated, or, if he has no real property in this state, the superior court of the county in which any of his personal property is situated, has jurisdiction to hear and determine all questions relative to any tax imposed by this part. If the transferor has property in more than one county, the superior court of any such county whose jurisdiction is first invoked has exclusive jurisdiction.