According to Wikipedia, their national rugby team wore black clothes in around 1905 and the team nickname "All Blacks" got popular. Then according to this artic

According to Wikipedia, their national rugby team wore black clothes in around 1905 and the team nickname "All Blacks" got popular. Then according to this article, the popularity of the rugby team then has made the color a popular national symbol in general. https://www.nzherald.co.nz/nz/grant-mclachlan-nzs-national-colour-is-black/GTDQLUA6VDRAIKZFKAU5T2KGLQ/ https://www.nzherald.co.nz/nz/grant-mclachlan-nzs-national-c... > The New Zealand Native Rugby Team first wore the silver fern on black, which then became our national colour.