They did more for the tournament than any other competing nation, and by a significant distance. If you ask the average league fan what were the most indelible images from the event, three stand out by a country mile.
First, the colour, commotion and chaos from Saturday's semi-final against England.
New Zealand league has never seen an atmosphere like it, and it's doubtful that the World Cup has either.
The second would be the Kiwis versus Tonga grudge match – a spectacular game that caught the imagination of the entire league world.
And the third was the clash of the Pacific nations, with the Siva Tau versus the Sipi Tau preceding a blood and thunder clash in Hamilton in the second week of the tournament.
Tonga also helped to delivered three of the biggest crowds of the event, with sellouts in Auckland (versus England) and Hamilton (versus New Zealand) and more than 20,000 going to see Samoa versus Tonga.
For all that Tonga, and their incredible fans, gave the tournament, it's time to give something back.
If the Kangaroos win the World Cup on Saturday night, why not start planning almost immediately for a game between Tonga and Australia?
It could be held in either Sydney or Brisbane – or if the sport really wanted to take a leap of faith – in the Tongan capital Nuku'alofa.
Imagine the scenes. Imagine the buildup. Imagine the match.
There are some obstacles – the most obvious financial – but these can be overcome with creativity, forward planning and genuine intent.
Across the last five weeks Tonga has given the greatest performance of any 'fourth nation' in international league since the days of France's magical teams in the late 1970s.
No one else has come close since.
Samoa almost touched the void in the 2014 Four Nations, while Scotland impressed many observers with their performance against the Kiwis and England last year.
But Tonga, in beating the Kiwis on home soil and pushing England to the limit, have smashed through that ceiling, creating a new frontier for the international game.
That can't be forgotten, and can't be allowed to fade back into the dust.