They gathered under heavy snow as lawmakers returned from winter recess. Similar protests were planned in nearly 30 cities across Canada Monday, the Canadian Broadcasting Corp. said.
Protesters said they want changes to the government's policies on aboriginal land control and other matters. The group said it is most upset about provisions in Parliament's omnibus budget bill they said violates their sovereignty and changes how lakes, rivers and other fishing spots are governed.
Conservative leaders defended the changes as good for business growth.
New Democrat MP Romeo Sangnash joined the protesters and called on Prime Minister Stephen Harper to keep aboriginal rights on the national agenda, in accordance with a U.N. statement on the rights of indigenous people Sangnash helped write in 2007.