In April 2003, the year New Zealand’s population hit 4 million, statisticians were predicting the country would hit at 4.8 million people in 2046. As in Europe and North America the country’s birth rate was falling, and no one quite knew whether mass immigration would – or even could – continue at pace. Instead, the pressing concern at the time was how to reverse the brain drain.

In the mid-2000s almost 40,000 New Zealanders were upping sticks each year. Miners and truck drivers were packing their bags for Queensland’s mining boom. Bankers and lawyers were taking up plum jobs in London. Teachers, nurses, and other public servants were comparing what they made in Wellington with what they might make in Washington or Ottawa.

And in that very brief moment it felt as if New Zealand was topping out. In 2008, the aspiring prime minister John Key took a camera crew to the capital city’s 35,000-seat stadium to illustrate just how big mass emigration was. The implication? We were, to repurpose a dangerous phrase, sending our best – to the US and beyond.

But the consensus among the commentariat was that Key’s stadium stunt was just that – a stunt – and even if he and his party came to power there was precious little they could do to reverse what was the natural order of things: a stronger Australian economy, its gravitational pull drawing in more and more New Zealanders.

Of course the commentators were right. The Australian economy remains stronger on most measures, and mass emigration was still a problem in the Key government’s early years. But one thing no one was anticipating was just how quickly the government would compensate for the brain drain with mass immigration.

In 2017, the Key government’s final year in power, net migration (the difference between those coming in or immigrating, including returning New Zealanders, and those going out or emigrating) was at a record 72,300. In 2015, net migration was at 58,000 and in 2013 it was a little shy of 50,000.

These are small numbers for countries such as Australia or the UK, sure, but for this country it was momentous. In the 20 years to 2014, average net migration to New Zealand was only 13,300.

And this year the country will reach another population landmark: 5 million people. It took more than 20 years to grow from 2 million to 3 million. It took 30 years for it to grow from 3 to 4 million. It took only 16 years to reach 5 million. And we are, because of that growth, a country transformed.

Population growth and the capital that comes with it are transforming the Auckland skyline. Tradespeople from Asia, the Philippines especially, are in good part responsible for rebuilding Christchurch after the devastating earthquake in 2011. Tourism and dairy, New Zealand’s leading export industries, are thriving off the back of migrant labour.

You can spot the transformation in schools, workplaces and universities, and the streets as well. Māori make up 16.5% of the population, up from 15% in 2013. We’re present in every part of the country’s private and public life, and in a way that was unthinkable half a century ago.

Māori make up 23% of MPs – a disproportionate share – and Māori lead or co-lead every sitting parliamentary party, bar Jacinda Ardern’s Labour. It’s fashionable to imagine New Zealand as a 1950s Britain – the temperate climate, a buttoned-down national character, and the things that were best about Britain like a cradle-to-grave welfare system – but in reality this is a Māori country.

For a very brief moment in the 80s that fact was at the heart of New Zealand’s constitution. The government understood the country as “bicultural”. Two peoples were in partnership, Māori and the European settlers who came after, and we’d run the show as equals. Sure, there was a gap – sometimes even a chasm – between promise and practice, but the aspiration was there.

The problem, though, is mass immigration from the 90s onwards quickly made biculturalism unworkable. In 2019, Asian peoples make up 15% of the population and Pacific peoples another 8%. In this new country only one kind of culturalism works: multi.

For people who oppose Māori reasserting their claim on political powerthis is great news. Māori are just one minority among many, the opponents insist, claiming they’re not even indigenous. But for the small number of Māori who tie their political claims to their demographic power it’s quite terrible. On current trends Asian peoples will overtake Māori as the second-largest ethnic group in New Zealand. This is an “ethnic-cultural tension point”, as the country’s leading demographer put it, confirming that in every settler colony, population politics is toxic.

Except when it isn’t. The truth is immigration isn’t diminishing Māori claims on political power. It’s strengthening those claims, pushing each one forward. At Ihumātaohundreds of land protectors are occupying the historic site and reclaiming it for the local tribes. Among the occupiers are groups such as “Asians for Tino Rangatiratanga” meaning Asians for Māori political power. Visitors to the land and supporters of the occupation include west African Islamic scholars, Cook Islands royalty, and indigenous Taiwanese people.

This is what sets New Zealand apart – and maybe above – other countries in the Anglosphere. Māori rights aren’t contingent on their status as a (growing) minority. Population power doesn’t secure our rights. The Treaty of Waitangi does. The country’s founding document reaffirms Māori political power (in the treaty’s own words it reaffirms our “tino rangatiratanga”). And equally so the treaty protects migrants, guaranteeing that New Zealand is their place to stand as well. The only thing the treaty expects of them is to recognise and respect Māori political power. The bargain is that simple and, if Ihumātao is any guide, it’s one that migrants are more than willing to make. This is the reason I’m so happy about New Zealand at 5 million.