By the 15th century the Moscow principality (or "Muscovy", "Moscovian Rus") had established its sovereignty over a large portion of ancient Ruthenian territory, including Novgorod and Pskov, and began to fight with Lithuania over the remaining Ruthenian lands. In 1547 the Moscow principality adopted the title of The Great Principat of Moscow and Tsardom of the Whole Rus and claimed sovereignty over "all the Rus'" — acts not recognized by its neighbour Poland. The Muscovy population was Eastern Orthodox and preferred to use the Greek transliteration "Rossia" (Ῥωσία) rather than the Latin "Ruthenia".