On the ground floor of the National Museum of Scotland in Edinburgh, one of its biggest displays is being carefully prepared for a 4,200 mile journey to its original home.

A 36ft (11m), one-tonne totem pole is returning to the Nisga’a Nation, one of the indigenous groups in what is now known as British Columbia on the west coast of Canada.

The totem pole has been in Scotland for almost a century since it was sold to the museum by Canadian anthropologist Marius Barbeau.

However, Nisga’a researchers say it was stolen without consent while locals were away from their villages for the annual hunting season.

The museum believes it acted in good faith but now understands that the individual who “sold” it to Barbeau did so “without the cultural, spiritual, or political authority to do so on behalf of the Nisga’a Nation”.

Last year it was agreed that the pole should be returned.

The totem pole was carved from red cedar in 1855 and is made almost entirely from a single piece of wood, with a small cap on top which can be separated

It originally stood in Ank’idaa village on the banks of the Nass River before it arrived in Scotland in 1929.

The totem, which features carved animals, human figures and family crests, tells the story of a Nisga’a warrior who was next in line to become chief before his death.

Dr Amy Parent, who is the Canada research chair in indigenous education and governance at Simon Fraser University in Vancouver, has led the move to return the pole.

Dr Parent, who has the Nisga’a cultural name Noxs Ts’aawit, said: “Within the pole itself we have crests that are carved – often represented by animals or humans – and within our particular pole there are two carved ravens as well as some other animals and then the chief sitting at the top.

“The ravens themselves represent the name Ts’aawit. He was an ancestral relative who passed away. He had lost his life defending our nation. He was a warrior and part of my name is attached to the name Ts’aawit.”

On Monday, a group of Nisga’a people, including Noxs Ts’aawit (Dr Parent), will carry out a private spiritual ceremony in front of the pole in Edinburgh before scaffolding is erected and it is encased in a protective cradle for its epic move.

Over the next month it will be manoeuvred out of a museum window and then flown across the Atlantic by the Canadian Air Force.

For the museum it is a painstaking operation.

Dr John Giblin, keeper of global arts culture and design at the National Museum of Scotland, said: “To prepare the pole to be able to leave the building we first needed to clear out entire galleries.

“We need to construct a scaffold around the pole, a cradle to have it lowered very carefully and it needs to be moved through the building.

“We need to close a road then it will be moved off to an air base.”

It’s the first time a national museum in the UK has returned a belonging of this type.

“I’m really pleased that the pole will be returning to its home where its spiritual, cultural, historical significance is most keenly felt,” Dr Giblin said.

The memorial totem is due to arrive in British Columbia in late September and will then be driven to the Nass Valley where it will be showcased in a Nisga’a museum with more than 300 objects that have been returned from around the world.

Noxs Ts’aawit said: “We are starting to feel really excited. Our hearts are at peace knowing we are doing the right thing and that we are re-establishing a new relationship with Scotland and with the museum.

“We are also in some ways still grieving and recognising that we have had many generations of family members, especially our matriarchs and our chiefs, many of whom have wanted to bring this pole home and we’re not able to within their lifetimes.

“We are recognising that these people in our family won’t be present, unfortunately they have passed away into the spirit world, and they have many children and others who will be feeling that grief.

“At the same time we’re feeling very uplifted and feeling like this is going to be a very historic moment for our nation and for Scotland.”