The metro excavation site located in Istanbul's Beşiktaş district, where 3,500-year-old cairn-type sepulchers were discovered, is most likely home to an ancient settlement, the head of Istanbul's Archaeological Museums said Monday.

Excavation teams had discovered 35 ancient "kurgan-type" graves during construction works as part of an extension to Istanbul's metro line.

Kurgans are a type of burial place usually characterized by earth and stones heaped over a burial chamber. They were characteristic of Bronze Age peoples, and have been found from the Altai Mountains to the Caucasus, Ukraine, Romania and Bulgaria. Kurgans were used in the Ukrainian and Russian steppes, and their use spread with migration into eastern, central, and northern Europe in the 3rd millennium B.Cs

Aerial footage of the area shows that teams are simultaneously carrying out excavations for the metro on the one side and archaeological work on the area where the tombs were discovered.

Istanbul Archaeology Museum Director Zeynep Kızıltan told Ihlas News Agency that they believe there had been a settlement near the tombs but they are still trying to figure out the exact location.

She noted that they will continue excavations in an area covering about 1,000 meters.

The cairn-type sepulchers date back to the Early Bronze Age, she said, adding that the discovery was groundbreaking as artifacts preceding the Byzantine Empire hadntarget="_blank"'>