Kurgan is the Turkic term for a tumulus; mound of earth and stones raised over a grave or graves, originating with its use in Soviet archaeology, now widely used for tumuli in the context of Eastern European and Central Asian archaeology.
The word is ultimately of Turkic origin, more specifically from Tatar according to the Oxford English Dictionary, from a word meaning "fortress".
The distribution of such tumuli in Eastern Europe corresponds closely to the area of the Pit Grave or Kurgan culture in South-Eastern Europe.
Kurgans were built in the Eneolithic, Bronze, Iron, Antiquity and Middle Ages, with old traditions still active in Southern Siberia and Central Asia. Kurgan cultures are divided archeologically into different sub-cultures, such as Timber Grave, Pit Grave, Scythian, Sarmatian, Hunnish and Kuman-Kipchak.
A plethora of placenames that include the word "kurgan" appear from Lake Baikal to the Black Sea.
Read more about Kurgan: Archaeology, Cultural Influences, Kurgan Hypothesis, Excavated Kurgans