On Thursday, New Zealand's parliament was thrown into chaos when members of the Maori Party ripped up a controversial bill and performed a traditional Maori war chant, known as a haka, in protest. This dramatic scene took place during a vote on a bill that could change the way the country interprets the 1840 Treaty of Waitangi, a historic agreement between New Zealand’s native Maori people and British settlers.

The Treaty of Waitangi promised that the Maori would keep their lands and tra...