A tumulus (plural tumuli) is a mound of earth and stones raised over a grave or graves. Tumuli are also known as barrows, burial mounds or kurgans, and may be found throughout much of the world. A cairn, which is a mound of stones built for various purposes, may also originally have been a tumulus.
https://upload.wikimedia.org/wikipedia/commons/thumb/1/16/Bi...
https://en.wikipedia.org/wiki/Tumulus

A kurgan (Russian: курга́н) is a type of tumulus constructed over a grave, often characterized by containing a single human body along with grave vessels, weapons and horses. Originally in use on the Pontic-Caspian steppe, kurgans spread into much of Central Asia and Eastern, Western and Northern Europe during the 3rd millennium BC

https://en.wikipedia.org/wiki/Kurgan

Inhumation and cremation in a flat grave were important features of Trzciniec culture. Cases of inhumation were discovered in Wolica Nowa, in the form of kurgans. Evidence of kurgan inhumation have been found at Łubna-Jakusy, whereas kurgan cremation has been found at Guciów.
https://en.wikipedia.org/wiki/Trzciniec_culture

under-barrow (pit) grave
underbarrow/under-barrow burial
sub-barrow burial
barrow burial

--------------------------------------------------
Note added at 5 days (2020-10-23 14:57:34 GMT)
--------------------------------------------------

Burial mound, artificial hill of earth and stones built over the remains of the dead. In England the equivalent term is barrow; in Scotland, cairn; and in Europe and elsewhere, tumulus.
https://www.britannica.com/topic/burial-mound

ARCHAEOLOGICAL POTENTIAL OF THE EARLY BRONZE AGE BARROW BURIAL GROUND IN SZCZEPANKOWICE: A GEOPHYSICAL SURVEY AND FIELD EVALUATION
http://www.ssa.archeo.uni.wroc.pl/57/SSA57_93-106.pdf

The Anglo-Saxon peoples had migrated to Britain during the fifth century CE, settling primarily along the eastern areas of what is now England. They were adherents of a pagan religion. The practice of Anglo-Saxon barrow burials had been adopted by the Merovingian dynasty Franks, who lived in what is now France, from the mid fifth century CE. It was from these Merovingian Franks that the Anglo-Saxons likely adopted the practice.
...
The first step in a barrow burial would have been the removal of a circular area of topsoil, which was then encircled with a ditch where the soil had been dug even deeper.[6] Archaeologist Martin Carver believed that this first stage had a symbolic significance in setting aside an inner and an outer zone between where the burial was going to be built and the outside world around it.
https://en.wikipedia.org/wiki/Anglo-Saxon_burial_mounds

Few people received a barrow burial, although it is not clear why they were chosen.
https://www.wondersofthepeak.org.uk/facts/grin-low-barrow/

In the light of the current state of research it is difficult to reco­gnize these bone remains as an inhumation under-barrow burial.
http://bazhum.muzhp.pl/media//files/Archeologia_Polski_Srodk...

This article published five dates for the Koshary Eneolithic cemetery [calibration after Kovalyukh, Nazarov 1999], one for the Mayaki settlement (of the Usatovo type), and six for the sub-barrow burial sites (cemeteries near the villages of Katarzhyno, Oleksandrivka, Khadzhider-1, Sadove, also identified as the Usatovo ones),
https://docplayer.pl/172460285-The-foundations-of-radiocarbo...