Who was The dominion of Canada was formed through?

Canada officially became a country on July 1, 1867 with the passing of the British North America Act (BNA) by the British Parliament. The first provinces were Quebec, Ontario, Nova Scotia, and New Brunswick.

The term "Dominion" is simply a historical reference to Section 3 of the BNA: "one dominion under the name of Canada". Canada was never known officially as "The Dominion of Canada", even though it was incorrectly labeled such at times.