Original sentence: 1st period - pre-Scythian and initial Scythian epoch: from the 9th to the middle of the 7th centuries BC.2nd period - early Scythian epoch: from the 7th to the 6th centuries BC.3rd period - classical Scythian epoch: from the 5th to the 4th centuries BC
Edited sentence: 1st period - pre-Scythian and initial Scythian epoch: from the 9th to the middle of the 7th centuries BC (Arjan-Chernogor kurgans).2nd period - early Scythian epoch: from the 7th to the 6th centuries BC (Maiemir-Kelermess kurgans).3rd period - classical Scythian epoch: from the 5th to the 4th centuries BC (Pazyryk-Chertomlyk kurgans).Archeological finds agree well with the records of the classical historians, and in addition provide a wealth of information, which in recent times was enriched by instrumented dating methods and genetical information.Most of what is known about Scythians was learned during archeological studies of the kurgans and kurgan fields, and re-examination of the early explorations