From Kaiapoi, Ngāi Tahu incorporated the southern sections of Ngāti Māmoe and Waitaha, who already occupied the South Island. The process was again one of small incursions, occasional bloodshed, piecemeal occupation and intermarriage rather than steady conquest. Kinship connections were forged to legitimise residence in each region. Ngāi Tahu occupied the Otago coast and the far south.
By the late 18th century, Ngāi Tahu and Ngāti Māmoe had established a tribal armistice. This was cemented in two marriages. The first was between Raki-ihia of Ngāti Māmoe and Hinehākiri, the cousin of Ngāi Tahu’s leading chief, Te-hau-tapunui-o-Tū. The second union was between Honekai, the son of Te-hau-tapunui-o-Tū, and Kohuwai, the daughter of Raki-ihia. These marriages were arranged at Kaiapoi and confirmed at Taumata in Otago.
The tribes mingle
While there were skirmishes between Ngāi Tahu and the tribes of Raki-ihia, the settlement was enduring. In fact, all the southern South Island signatories to the Treaty of Waitangi in 1840 were descendants of this union, and of all three tribes, Ngāi Tahu, Ngāti Māmoe and Waitaha.
The West Coast
The leading chief of Ngāi Tahu in Canterbury was Tūrākautahi, who decided that he and his kinsmen needed to learn the genealogy of the land. Consequently, an expedition was mounted to the West Coast to learn from the tribes there. Stories typically hold that only Tūrākautahi and his kinsman Te-ake survived the traditional school of learning, while their companions were slain for breaking various customs.
How pounamu formed
The term pounamu (greenstone, or New Zealand jade) includes the mineral species nephrite and bowenite. Found only in the South Island (at sites including Westland, inland Otago and Milford Sound) it was the most valuable stone used by Māori. One story of its origins concerns the taniwha (monster) Poutini, a guardian for Kahue, the god of pounamu. At Mayor Island, east of the Coromandel Peninsula, Poutini abducted the beautiful Waitaiki. Pursued to the South Island by Waitaiki’s husband, Poutini eventually hid his captive in Westland’s Arahura River. About to be discovered, Poutini transformed Waitaiki into pounamu. He then escaped to sea, where he still guards the pounamu of the West Coast. Arahura River greenstone is broken from the body of Waitaiki, in the headwaters.
The two West Coast tribes, Ngāti Wairaki and Ngāti Tūmatakōkiri, were likely to have originated from the East Coast of the North Island. Ngāti Wairaki, in particular, shared tight kinship connections with Ngāi Tahu and Paikea, as their common ancestor was the famed Tura. Both tribes were eventually subsumed as sub-tribes of Ngāi Tahu.
The West Coast, with its rich supply of pounamu (greenstone), came into Ngāi Tahu’s possession, and Kaiapoi pā became the centre of an extensive trade in this most valued of stones.
Ngāi Tahu’s final boundaries
By this stage, Ngāi Tahu’s tribal territory covered most of the South Island, running from Te Parinui-o-whiti (White Bluffs) on the east coast to Kahurangi Point on the West Coast, and southwards to Rakiura (Stewart Island).