The word "Tribal" has been used to describe island tattoos that are now in fashion. When referring to a Tongan or Samoan or most other Pacific Island tattoos, the word "Tribal" is incorrect. Referring to Islanders as living in 'tribes' is a racist notion used to separate people according to how civilized they are.
Tongans never lived in tribes and their tattooing practices weren't practiced within a tribal context, so do not refer to them as "tribal tattoos".