Russia has also had a long history of militarism continuing on to the present day driven by her desire to protect her western frontier which has no natural buffers between potential invaders from the rest of continental Europe and her heartlands in European Russia. Ever since Peter the Great's reforms, Russia became one of Europe's great powers in terms of political and military strength. Through the Imperial era, Russia continued on her quest for territorial expansion into Siberia, Caucasus and into Eastern Europe, eventually conquering the majority of the Polish-Lithuanian Commonwealth.