Rāniera Te Ahiko was born in the late eighteenth or early nineteenth century at Taumata-ō-hē pā near the junction of the Mangatahi Stream and the Ngaruroro River in Hawke's Bay. This pā belonged to Te Uamairangi, principal chief of Ngāti Te Ūpokoiri, and his son Tūhotoariki. Rāniera's parents, Te Kere of Ngāti Mahuika hapū of Ngāti Kahungunu and Pungarehu of Ngāti Uranga, were living at the pā under Te Uamairangi's mana. The ancestral lands of Rāniera's family centred on Ōhiti and Lake Rūnanga, about a mile up the Ngaruroro from Ōmahu, and part of Rāniera's youth was spent at Whangaitete, on an island in Lake Rūnanga.
Rāniera's life was to be shaped by his upbringing amidst the warlike Ngāti Te Ūpokoiri. He witnessed many battles in which they were involved, and came to know intimately their remote fastnesses in the Ruahine Range and the upper Ngaruroro River. After the battles with Ngāti Kahungunu and Ngāti Te Whatuiāpiti at Mangatoetoe and with Ngāti Kahungunu and Ngāti Kurapare at Kirikiritatangi, Rāniera was living with Ngāti Hinepare at Te Korea on the Mangaone River near present-day Dartmoor when, sometime before 1820, Tangiteruru and Te Peehi Tūroa raided Hawke's Bay. The local tribes gathered at Te Rae-o-Tahumata near Ōmāhu under the protection of the chiefs Whakatō and Pakapaka, staying together until the danger had passed.
On the death of Te Uamairangi, his grandson Te Wanikau assumed his mantle as principal chief. For over 30 years Rāniera's fortunes were to be intertwined with those of Te Wanikau. His intelligence and command of tribal history earned him respect and he now lived among Ngāti Te Ūpokoiri as their historian.
In 1820 Ngāti Tūwharetoa and Ngāti Te Ūpokoiri unsuccessfully besieged Ngāti Kahungunu's island pā at Te Roto-a-Tara, near Pukehou. Ngāti Te Ūpokoiri then withdrew to inland Pātea, in the upper Rangitīkei region, while Rāniera accompanied Te Wanikau on a visit to his relatives at Lake Rotoaira. He married Te Wanikau's sister during the stay; they were to have no children. He later married Hokepera, of Ngāti Hinepare and Ngāti Hikawera, with whom he had one child.
In 1823 a second expedition of Ngāti Tūwharetoa and Ngāti Te Ūpokoiri was defeated by a combined force of Nga Puhi, Ngāti Te Whatuiāpiti and Ngāti Kahungunu at Te Whiti-o-Tū on the upper Waipāwa River; Rāniera then lived with his family at Pohokura in the mountains for a year as a refugee. Te Wanikau continued on to Taupō with Ngāti Tūwharetoa, and Rāniera was later taken by Te Rarotawhana to join him there.
About 1824 Ngāti Te Ūpokoiri went to Kapiti Island to get firearms for a further expedition. They then accompanied Te Momo-a-Irawaru to Te Roto-a-Tara, where the subsequent battle saw Ngāti Te Ūpokoiri and Ngāti Raukawa suffer great loss of life. The surviving Ngāti Te Ūpokoiri chiefs sought refuge in the eastern Ruahine with Rāniera, who had remained behind. They launched reprisal raids on Poukawa and Kairākau, then journeyed to exile in Manawatū, living with the Rangitāne chiefs Tīweka and Takore at Te Kuripaka. They were later joined by Te Wanikau.
Te Wanikau died in Manawatū in the early 1840s, and in February 1850 William Colenso recorded the departure of the chiefs of Heretaunga to raise his bones. Kurupō Te Moananui of Ngāti Kahungunu then invited Ngāti Te Ūpokoiri to return to Heretaunga. Rāniera accepted the invitation, and asked Pāora Kaiwhata, chief of Ngāti Hinepare, to prepare cultivations for him at Ōmihi on the Ngaruroro River. He arrived back in August 1850 with his cousin Āperahama Kaipipi.
In 1851 Rēnata Kawepō, the successor to Te Wanikau, went to Manawatū to gather the remnants of his people. A section of them returned and established temporary quarters at Pokonao near William Colenso's mission station. They remained there for perhaps two years before joining Rāniera at Ōmāhu. The remainder of Ngāti Te Ūpokoiri returned in two migrations, one in 1853, the other in 1861.
In 1857 Rāniera joined Te Moananui and Rēnata Kawepō against Te Hāpuku who was selling land in which they all had interests. After the defeat of Te Hāpuku at Te Pakiaka, Rāniera moved to Ngāhape between Ōmāhu and Crissoge station. He was to live there for the next 30 years. He gave his home at Ōmāhu to his niece Hoana Pakapaka and her husband, Te Waata Raka-i-werohia. He also took Kawepō to inland Pātea to familiarise him with the lands over which he was now chief.
During the 1860s Rāniera witnessed many changes in Hawke's Bay: a flour mill was established at Paherumanihi, much land was sold to Europeans, and there was conflict with Hauhau. Most importantly, Rāniera entered a highly productive and valuable period as an expert witness in the Native Land Court. He quickly adapted to the unfamiliar milieu of the court, and with each succeeding case his reputation as a historian grew. He gave evidence on the Pukehamoamoa block in 1880, and between 1884 and 1893 was a witness for Ngāti Te Ūpokoiri and related hapū in most of the inland Pātea hearings. His evidence in the various hearings of the Ōwhāoko, Mangaohane and Awarua blocks has left a rich and detailed documentation of Ngāti Te Ūpokoiri tribal history.
In the Ōmāhu case, which began in July 1889, Rāniera was the principal witness when Airini Donnelly, grand-daughter of Kawepō's sister, Ērena Mekemeke, and Wī Broughton, a relation of Kawepō's, contested Kawepō's legacy. At one point the court was requested to adjourn to Rāniera's residence to take evidence; he was too unwell to come to court and by reason of his age and illness would 'perhaps be unable to re-enter this Court again.' In the judgement Rāniera was described as 'a clear-headed witness, well acquainted with the history of this land.' Even after his death his evidence was quoted in court. Ānaru Te Wanikau perhaps summed up the situation best in his evidence in the Timahanga case: Rāniera, he said, had the best knowledge; his evidence was correct.
Rāniera Te Ahiko died at Ōmāhu, probably on 17 April 1894. His body was taken to Ōhiti for burial. His only son, Mohi Rāniera, had died in the early 1870s leaving Rāniera with five grandchildren to raise. He had also gathered the grandchildren of Hinetoi, a relative who had been living among Ngāti Porou since her capture at the battle of Motukūmara, and brought them back from East Cape to live with him. Rāniera's line continues through his two grand-daughters, Ria Mohi and Te Rōhutu Mohi.