The Atikamekw First Nation has declared sovereignty over 30,888 square miles of Canadian territory.
The unilateral decision, announced on Monday, was based on the Supreme Court judgment that recognizes ancestral rights of First Nations in British Columbia.
The ruling, made in June, was considered historic because it was the first time that Canadian authorities recognized a First Nation title to a specific tract or land.
This tittle protects the First Nation's territories, commonly used for fishing, hunting and construction.
However, if a First Nation blocks a development on its land, it can still go on if the government proves that the development is pressing and substantial and meet its fiduciary duty to the Aboriginal group.
The Atikamekw First Nation announcement was made by its leader, Constant Awashish, who asserted that any development project in its territory, in the Nitaskinan region, will have to be approved by the community.
"Gone are the days of negotiating the rights of the Atikametw, which have not been surrendered, for the benefit of a state that imposes its rules as if such rights do not exist," Awashish said at a news conference Monday.