Lazar Hrebeljanović was a medieval Serbian ruler who created the largest and most powerful state on the territory of the disintegrated Serbian Empire. Lazar's state, referred to by historians as Moravian Serbia, comprised the basins of the Great Morava, West Morava, and South Morava rivers. Lazar ruled Moravian Serbia from 1373 until his death in 1389. He sought to resurrect the Serbian Empire and place himself at its helm, claiming to be the direct successor of the Nemanjić dynasty, which went extinct in 1371 after ruling over Serbia for two centuries. Lazar's programme had the full support of the Serbian Orthodox Church, but the Serbian nobility did not recognize him as their supreme ruler. He is often referred to as Tsar Lazar Hrebeljanović ; however, he only held the title of prince.

The Serbian Empire was a medieval Serbian state that emerged from the Kingdom of Serbia. It was established in 1346 by Dušan the Mighty, who significantly expanded the state.