query: When was the city of Merv established?
passage: Merv
Under the Achaemenid Empire (c. 550–330 BC), the historical record mentions Merv as a place of some importance: under the name of Margu it occurs as part of one of the satrapies in the Behistun inscriptions (ca. 515 BC) of the Persian monarch Darius Hystaspis. The first city of Merv was founded in the 6th century BC as part of the Achaemenid expansion into the region[2] of Cyrus the Great (559–530 BC), but later strata deeply cover the Achaemenid levels at the site.
passage: Chernihiv
Chernihiv was first mentioned in the Rus'-Byzantine Treaty (907) (as (Chernigov)), but the time of establishment is not known. According to the items uncovered by archaeological excavations of a settlement which included artifacts from the Khazar Khaganate, it seems to have existed at least in the 9th century. Towards the end of the 10th century, the city probably had its own rulers. It was there that the Black Grave, one of the largest and earliest royal mounds in Eastern Europe, was excavated in the 19th century.