Researchers often label the time from about 1280 to about 1450 the Archaic period or "Moa-hunter period" – after the moa, the large flightless bird that formed a large part of the diet of the early Polynesian settlers. During this period Māori adapted to their new environment, but culturally they changed little from their tropical Pacific ancestors. The immigrants brought many edible plants from their home islands in the central Pacific, and of these "kūmara" (sweet potato) would become the most important. The far South of Aotearoa, however, had too cold a climate for growing any of these crops. Large quantities of tī tubers were eaten that were slow-cooked in large or (earth ovens) to get rid of the poison and to produce a slightly sweet pulp. Shellfish, fish, sharks and seals were also common foods. Native dogs () and rats were brought from the Pacific Islands. The introduction of rats undoubtedly had more impact on New Zealand wildlife than any other organism apart from humans. The dogs aided in hunting but also served as food.