Original: It had traditionally been considered closely related to Verbenaceae, but in the 1990s, phylogenetic studies showed that many genera classified in Verbenaceae belong instead in Lamiaceae.
Simplified: It has been considered closely related to Verbenaceae but several recent phylogenetic studies have shown that a lot of the genera classified in Verbenaceae belong instead in Lamiaceae, whereas the core genera of Verbenaceae are not closely related to Lamiaceae and are more closely related to other members of the Lamiales.