The Yamnaya or Yamna culture, also known as the Pit Grave culture or Ochre Grave culture, is a late Copper Age to early Bronze Age archaeological culture of the region between the Southern Bug, Dniester, and Ural rivers, dating to 3300–2600 BC. It was discovered by Vasily Gorodtsov following his archaeological excavations near the Donets River in 1901–1903. Its name derives from its characteristic burial tradition: yamnaya (ямная) is a Russian adjective that means 'related to pits', as these people buried their dead in tumuli (kurgans) containing simple pit chambers. Research in recent years has found that Mykhailivka, on the lower Dnieper River in Ukraine, formed the core Yamnaya culture.