Immigration
The Tanners are immigrants to New Zealand, coming from Britain in search of a better life (a very altruistic and positive reason). However, their immigration to New Zealand has unexpected consequences: they hurt the Māori, or aboriginal people of New Zealand.
The Tanner's home
The Tanners decide to immigrate to New Zealand in search of more opportunities. However, rather than living in a place where there was a tremendous amount of opportunity and opportunity to advance, the Tanners live in an isolated place far away from their neighbors.
Mrs. Tanner's pregnancy
At the start of the short story, Mrs. Tanner is pregnant and about ready to give birth. Rather than getting herself into a position where she could easily receive medical care (if needed), she decides to give birth in her home, far away from medical care. People inherently value their life and health; not going closer to medical care is unexpected.
Colonialism
New Zealand had seemingly very little value (and very few natural resources), making it seemingly not very appealing to be colonized. However, in a move that made very little logical sense, the British Empire shockingly expended a considerable amount of resources to colonize New Zealand.
Violence
The Tanners never had to deal with any serious violence despite living in a remote area in a country that they were unfamiliar with. The Māori, however, the people the British ostracized and expelled from their own country, dealt with tremendous violence.
