Horatio Gordon Robley was a British soldier of the 68^th Durham Light Infantry who served in New Zealand during the New Zealand Wars (1845-72). Arriving Auckland in 1864, Robley took a great interest in New Zealand, particularly Māori language and culture, and purchased several books to find out more. His major interest was in tā moko, Māori tattooing, obtained from sketching the facial tattoos of dead Māori following the British defeat at Gate Pā which took place shortly after his arrival in New Zealand.

Tā moko is highly prized in Māori culture, serving as a symbol of Mana (spiritual power and authority) and high status. Receiving moko was a symbol of adulthood and was accompanied by a series of rituals. Tattooists (tohunga-tā-moko) were also seen as tapu, or sacred. The practice started to fall out of fashion in the 1860s as European settlers (Pākehā) became more influential in the country, but it is currently undergoing a resurgence in popularity among modern Māori who wear moko as a symbol of cultural identity.

Robley maintained his interest in Māori after leaving New Zealand and gradually formed a collection of examples of tā moko, particularly mokomokai, the preserved tattooed heads of Māori, of which he owned 35.

This book was published in 1896, as a result of his research, and became an important reference work on the art of tā moko. He offered his collection of mokomokai to the New Zealand government in 1908, this was refused, and many of the heads were sold to the American Museum of Natural History. The collection was repatriated in 2014 at a ceremony at Te Papa Tongarewa, the national museum of New Zealand, in Wellingon.