The first of these tribes to settle permanently in the South Island was Waitaha. Modern ethnology and archeology, as well as tribal history describe these people as a mixture of loosely related peoples, with a similar culture. There are many people today who are descendants of these early settlers, and who consider themselves distinct from the Ngai Tahu tribe as a whole.
The second tribe, Kati Mamoe, arrived in the South Island in the sixteenth century. The people migrated from the East coast of the North Island around the city of present-day Napier, and hold close links to the tribe of that region (Ngati Kahungungu). Making their way southward, they stopped for a period at the southern tip of the North Island, then, when pressures for land and resources became too much, they moved over the stretch of water to the South Island. Migrating down the East coast they settled principally at Kaikoura, although some families eventually travelled further south to settle amongst Waitaha. Kati Mamoe have a distinct dialect, which can be seen in the replacement of "ng" with the harder "k" sound. Thus, whereas other tribes name themselves "Ngati", the southern "Kati" is more commonly used. Present day place names like Aoraki/Mount Cook, Wanaka, the Waitaki river, and Moeraki reflect the settling of this tribe. Linguists have traced the descendants of this tribe by their dialect, and even today, it is not uncommon to hear a dialect that is not heard in other parts of New Zealand.
The third tribe to make it's mark in the South Island, was KaiTahu. This invasion was not, as some scholars believe, a single migration, but rather a collection of forays southward from the Wairarapa and Wellington, by descendants of Tahu Potiki. Eventually, by conquest and intermarriage Kai Tahu came to be the dominating force of the South Island.
Most people today who call themselves Ngai Tahu, have ancestors in all three tribes.