Complex sentence: He promoted contacts with francophones in other parts of North America outside of Quebec including Western Canada and New England; at that point in history those francophones had not yet been assimilated to the extent they would be in the future.
Split into simpler sentences: He promoted contacts with francophones in other parts of North America outside of Quebec including Western Canada and New England. Those francophones had not yet been assimilated into the English-Canadian or American culture to the extent they would be in the future.