Stolen??  Take a glimpse at some of the common language found in the Number Treaties:

AND WHEREAS, the said Indians have been notified and informed by Her Majesty's said Commission that it is Her desire to open for settlement, immigration, trade, travel, mining, lumbering and such other purposes as to Her Majesty may seem meet . . . 

. . . and to obtain the consent thereto of Her Indian subjects inhabiting the said tract, and to make a treaty. . 

. . . the said Indians DO HEREBY CEDE, RELEASE, SURRENDER AND YIELD UP to the Government of the Dominion of Canada, for Her Majesty the Queen and Her successors for ever, all their rights, titles and privileges whatsoever, to the lands . . . 

No one stole anything from natives.  Natives willingly chose to enter into treaties in order to advance their people's position by aligning themselves with a superior civilisation; a civilisation that had discovered the wheel, metallurgy, firearms and more.