The Inquiry into Abuse in Care says abuse in state care of disabled, deaf and people who suffered mental distress was overt and systemic.
The Royal Commission opens a public hearing on Monday in Auckland focusing on state institutions which provided care for these people between 1950 and 1999.
Twenty-three survivor witnesses will give evidence about their time in the Kimberley Centre in Levin, Templeton Centre, near Christchurch, Porirua Hospital, Tokanui Hospital, near Te Awamutu, Kelston Deaf Education Centre/van Asch Deaf Education Centre in Auckland, Homai School, and Carrington, Kingseat and Māngere Hospitals in Auckland.
The hearing will examine the use of control and restraint in disability and mental health care.
It will also look at the adequacy and availability of complaints procedures and impacts of long-term institutionalisation on survivors and their whānau.
Lead counsel assisting the commission, Ruth Thomas, said there was physical, sexual, psychological and emotional abuse, and also educational and cultural neglect.
The length of time some people spent in state care was a unique part of the evidence that had been gathered for the hearing, she said.
''Particularly people with learning disabilities who were placed in psychopaedic institutions. Some of them remained there for decades and decades of their lives, so we have gathered evidence for people who spent 40-plus years at Kimberley, or 40-plus years at Templeton.
''That is a really important piece of New Zealand's history to share and for people to understand, because it hasn't really seen the light of day and this is our opportunity to share that.''
Thomas said there would be evidence from survivors of overt abuse across all of the state institutions.
''You will hear about a loss of personal identity and a loss of person-hood. These institutions were based on routine and regimes, so that people had no choice over how they would spend their days.
"So many people were herded into the meal room, and then herded out like cattle to be required to sit on the toilet, there was no privacy in that.
"There were no doors in the shower blocks or toilet areas and then herded into the villa day-rooms where people spent their days sitting, or staring, snoozing in chairs, with no purposeful activities.''
Thomas thanked the survivors who had engaged with the Royal Commission.
''It is their precious taonga that we have been privileged to receive and it is through their voices that we can analysis the evidence that they have shared with us and make some findings and recommendations that will go to the government.''
''In terms of this evidence, it is a piece of New Zealand's history that has not been previously heard and it has been shut away, out of sight, out of mind and it is now time for it to be shared and for all New Zealanders to listen and challenge themselves about the way we have treated disabled people, deaf people, and people in mental distress.''