A related issue concerns the appropriate periodisation of NZ history. One broad schema suggests the following periods:

• Maori arrival and settlement

• Europeans to 1840

• British sovereignty and settlement

• War, expansion and depression

• Liberal to Labour

• The later 20th century

John Wilson. 'History', Te Ara - the Encyclopedia of New Zealand, updated 25-Sep-2007

A descriptive review of recent policy evetns can be found at:
Social Policy Events Report Monitoring the impact of social policy, 1980-2001: Report on significant policy events   

There is also the issue of the appropriate ‘regionalisation’ within New Zealand. Different schema seem appropriate to different purposes.

1. Iwi distribution (and also ‘canoes’): http://www.takoa.co.nz/iwi_maps.htm
2. “Provincial Governments”:
3. Regional council areas: http://newzealand.govt.nz/browse/government-local-central-regional/regional-councils/

An earlier survey of this issue can be found at:  Charles Crothers (1984)  "Patterns of Regional Social Differences in New Zealand", Australia and New Zealand Journal of Sociology, 20: 365-376.