Because the duchy was outside of the core Holy Roman Empire, the prince-electors of Brandenburg were able to proclaim themselves King of <answer>Prussia</answer> beginning in 1701. After the annexation of most of western Royal <answer>Prussia</answer> in the First Partition of the Polish-Lithuanian Commonwealth in 1772, eastern (ducal) <answer>Prussia</answer> was connected by land with the rest of the <answer>Prussia</answer>n state and was reorganized as a province the following year (1773). Between 1829 and 1878, the Province of East <answer>Prussia</answer> was joined with West <answer>Prussia</answer> to form the Province of <answer>Prussia</answer>.
What time period did East Prussia and West Prussia join to become Prussia?
Prussia