When New Zealand played their last international match this year
The cricket culture in New Zealand is quite different from others. New Zealand doesn't prefer a hectic cricket schedule; their board prefers providing appropriate time for the Kiwis to spend time with their family, also ensuring that they're fresh and fine before their cricket matches.
New Zealand hardly plays any matches during the snowfall season. As a result, the volume of their international matches is pretty low.
The Blackcaps played their last international match against England on 30 March 2018. Since then, they've played no international cricket match.
Let's see what was going on in the cricketing world when they played their last international match:
#1 Steve Smith was the No.1 Test batsman
The infamous 'Sandpaper-gate' took place on 24 March 2018. After some investigation, Steve Smith, David Warner and Cameron Bancroft were adjudged as the culprits of the whole incident. However, Steve Smith was still the No.1 Test batsman back then by a fair margin.
Even after Steve Smith was banned by the official cricket board of Australia for 12 months, he was not excluded from the ICC Test Batsman Rankings. So, when New Zealand played their last Test match, Steve Smith was still the No.1 Test Batsman in the world, as per the ICC Rankings.
#2 Afghanistan and Ireland were yet to play their first Test match
When New Zealand played their last Test match, Afghanistan and Ireland were yet to make their Test debut. Although both the teams were handed the Test status by the ICC in 2017, they made their Test debut in 2018.
While New Zealand played their last international match on 30 March 2018, Afghanistan and Ireland made their Test debut on 14 June and 11 May respectively, this year. Thus, when New Zealand played their last international match, Ireland and Afghanistan were yet to make their Test debut in international cricket.