The 1670 Hudson’s Bay Company Royal Charter, considered among one of Canada’s founding documents, has been sold for C$18m ($13m; £9.6m) to two of the country’s richest families.

The 355-year-old charter, which granted the Hudson’s Bay Company wide-ranging powers over large swaths of what is now Canada, ended up at auction when the corporation filed for bankruptcy over the summer.

The offer by firms owned by the Weston family and David Thomson, chairman of Thomson Reuters, will keep the historically significant document in Canada.

And the charter – once housed in a rural manor in the UK in World War Two during the blitz – will be under shared custody of various Canadian museums and archives.

The bid also includes a C$5m donation to those custodian musuems for stewardship and public education around the document.

A court still needs to approve the final sale.

The Hudson’s Bay Company said in a statement on Wednesday that “the Charter will be placed in the care of trusted institutions committed to, among other things, working in consultation with Indigenous communities so the Charter’s complex history can be acknowledged, interpreted and shared with all Canadians”.

The Archives of Manitoba, the Manitoba Museum, the Canadian Museum of History and the Royal Ontario Museum will have joint possession of the document.

Granted by King Charles II in 1670, the charter vested power to the company, a key player in the powerful continental fur-trade that later became an iconic Canadian department store, to make laws and establish colonies in parts of now modern-day Canada.

Hudson’s Bay Company “was able to use the language of this charter to operate as both a corporation and as a government,” Cody Groat, assistant professor of history and indigenous studies at Western University, told the BBC.

There were early colonies where it could pass legislation and negotiate treaties with indigenous peoples, he said – “all kind of associated with this initial document, signed by King Charles II”.

The charter also served as the legal foundation for the company to sell its North American territories to Canada in 1869, without the consent of the indigenous people living there, according to Mr Groat.

The document itself was initially kept at Windsor Castle then moved to the company’s headquarters in London until 1940. During World War Two it was stowed at an estate in Hertfordshire for safekeeping before finally finding a home at the new Toronto headquarters of the Hudson’s Bay Company in the 1970s.

Many of the Hudson’s Bay Company’s archival records were donated to the province of Manitoba in the 1990s, but not the charter.

When the firm, facing massive debts and declining sales, filed for bankruptcy and liquidated all its department stores last summer, there was pressure to have the charter – a valuable corporate asset – somehow kept in the public domain.

“We saw this sustained push-back over time, and we started to see these wealthy families and corporations start making quite sizeable offers to purchase this and then donate it immediately to a public institution,” said Dr Groat.

Eventually, DKRT Family Corp, under David Thomson, and Wittington Investments, Ltd, owned by the Weston family, emerged as the successful bidders in Wednesday’s auction.