The Treaty of Waitangi was a written agreement made in 1840 between the British Crown (the monarch) and more than 500 Māori chiefs. After that, New Zealand became a colony of Britain and Māori became British subjects.he Treaty of Waitangi, New Zealand’s founding document, was meant to be a partnership between Māori and the British Crown. Although intended to create unity, different understandings of the treaty, and breaches of it, have caused conflict.