During the nineteenth century, voting in New Zealand was limited to men who owned, and could prove they owned land. It was a complex system which, if I understand correctly, entitled people with more land to have multiple votes (but I wouldn't quote me on that).

From 1858, the colonial government, which was made up entirely of white men, faced resistance to both their authority, and their efforts to extend government control into parts of the country that were mainly inhabited by Māori, and where the European population was sparse. This resistance was largely represented by the Kīngitanga from 1858-64, and then by the Pai Mārire and Ringatū movements.

The Kīngitanga was a land league, that sought to protect Māori sovereignty by refusing to sell land to Eurpoeans. They were immensely powerful, as they controlled an enormous area of land south of Auckland, which was the capital city at the time. The resistance and the need for land for expansion eventually led to war breaking out in 1863 in the Waikato. Likewise, the Pai Mārire and Ringatū movements had episodes of violence, with both Pākehā and Māori being killed.

The second aspect of this question is land ownership. Māori owned large tracts of land, as I mentioned above. But Māori land wasn't held under the same title as European land. Where Europeans owned land as individuals, with Mr. Smith owning 10 acres, and Mr. Jones owning 20 acres, Māori ownership was communal, and titles for Māori land were really just European bureaucracy trying to shoehorn Māori custom into a familiar legal framework. The outcome was messy, with titles being issued for Māori land with large numbers of owners, sometimes over a hundred. This also led to problems in selling, when one person out of the collective wanted to sell, and the courts would enforce their position in an effort to separate Māori from their land (but that's another question entirely). What this also meant, is that the majority of Māori were ineligible to vote, because very few of them could show land ownership.

It was in this context that the colonial government sought to give Māori a semblance of political participation, and hopefully assuage ill feeling towards the government. To that end, suffrage was extended to all Māori men over the age of 21, escaping the issues of Māori ownership, but also confining Māori participation in politics somewhat - this was done by creating the Māori seats. In the original iteration, there were four seats, separated into Northern Māori, Eastern Māori, Western Māori, and Southern Māori. Because parliamentary seats in New Zealand are organised by population, Māori should have been given at least 12 seats for full representation. By limiting the number to four, Māori political power was weakened on multiple fronts: the Māori electorates diverted votes that might otherwise have shaped general electorate results, as well as fencing Māori into the smaller system of representation; and in the general electorates, the remaining Māori vote was negated by the larger numbers of European voters.