<P> Leadership was based on a system of chieftainship, which was often but not always hereditary, although chiefs (male or female) needed to demonstrate leadership abilities to avoid being superseded by more dynamic individuals . The most important units of pre-European Māori society were the whānau or extended family, and the hapū or group of whānau . After these came the iwi or tribe, consisting of groups of hapū . Related hapū would often trade goods and co-operate on major projects, but conflict between hapū was also relatively common . Traditional Māori society preserved history orally through narratives, songs, and chants; skilled experts could recite the tribal genealogies (whakapapa) back for hundreds of years . Arts included whaikōrero (oratory), song composition in multiple genres, dance forms including haka, as well as weaving, highly developed wood carving, and tā moko (tattoo). </P> <P> New Zealand has no native land mammals (apart from some rare bats) so birds, fish and sea mammals were important sources of protein . Māori cultivated food plants which they had brought with them from Polynesia, including sweet potatoes (called kūmara), taro, gourds, and yams . They also cultivated the cabbage tree, a plant endemic to New Zealand, and exploited wild foods such as fern root, which provided a starchy paste . </P> <P> The first Europeans known to reach New Zealand were the crew of Dutch explorer Abel Tasman who arrived in his ships Heemskerck and Zeehaen . Tasman anchored at the northern end of the South Island in Golden Bay (he named it Murderers' Bay) in December 1642 and sailed northward to Tonga following an attack by local Māori . Tasman sketched sections of the two main islands' west coasts . Tasman called them Staten Landt, after the States General of the Netherlands, and that name appeared on his first maps of the country . In 1645 Dutch cartographers changed the name to Nova Zeelandia in Latin, from Nieuw Zeeland, after the Dutch province of Zeeland . It was subsequently anglicised as New Zealand by British naval captain James Cook of HM Bark Endeavour who visited the islands more than 100 years after Tasman during 1769--1770 . Cook returned to New Zealand on both of his subsequent voyages . </P> <P> Various claims have been made that New Zealand was reached by other non-Polynesian voyagers before Tasman, but these are not widely accepted . Peter Trickett, for example, argues in Beyond Capricorn that the Portuguese explorer Cristóvão de Mendonça reached New Zealand in the 1520s, and the Tamil bell discovered by missionary William Colenso has given rise to a number of theories, but historians generally believe the bell' is not in itself proof of early Tamil contact with New Zealand' . </P>

When did the british arrived in new zealand