[10] The formation of genuine nomadic pastoralism itself happened in the early 1st millennium BC due to climatic changes which caused the environment in the Central Asian and Siberian steppes to become cooler and drier than before.

[11] The Agathyrsi originated as a section of the first wave[14] of the nomadic populations who originated in the parts of Central Asia corresponding to eastern Kazakhstan or the Altai-Sayan region,[15] and who had, beginning in the 10th century BC and lasting until the 9th to 8th centuries BC,[16] migrated westwards into the Pontic-Caspian Steppe regions, where they formed new tribal confederations which constituted the Chernogorovka-Novocherkassk complex.

[22] Thanks to their development of highly mobile mounted nomadic pastoralism and the creation of effective weapons suited to equestrian warfare, all based on equestrianism, these nomads from the Pontic-Caspian Steppes were able to gradually infiltrate into Central and Southeast Europe and therefore expand deep into this region over a very long period of time,[23][8] so that the Chernogorovka-Novocherkassk complex covered a wide territory ranging from Central Europe and the Pannonian Plain in the west to Caucasia in the east, including present-day Southern Russia.

[25] After their displacement, the Agathyrsi settled in the regions surrounding the Eastern Carpathian Mountains corresponding to the territories presently called Moldavia, Oltenia and Transylvania,[36] although they also may have been one of the peoples who had free access to the Wallachian and Moldavian Plains along with the Scythians.

[25][40] And, beginning in the 6th century BC, the Agathyrsi were organising into fortified settlements, such as the ones at Stâncești and Cotnari, which acted as important centres of the Getae.

[25] A section of the displaced Agathyrsi might also have migrated more southwards into Thrace proper, where a group of this people was located on the Haemus Mons by Stephanus of Byzantium.

[42] By the early 2nd century BC, the Trausi had migrated to the east of the Hebrus river in the hinterland of Maroneia and Aenus, and they soon disappeared from history after being conquered by the kingdom of the Sapaei.

[56] In the middle of the 5th century BC, the Hallstatt culture developed into the La Tène culture, whose people are identified with the Celts, who by the late 5th century BC were moving to the east along the upper Istros and initially settled in Transistria before moving into the Pannonian Steppe where lived the Sigynnae and later into the mountainous regions where lived the Agathyrsi.

[58] The Agathyrsi were barely mentioned again in outside sources after Herodotus of Halicarnassus described them in the 5th century BC,[3] and it is unknown for how long they were able to maintain their Agathyrsian identity.

[25] The Agathyrsi hence disappeared from history in a process typical of most Scythic peoples who back then formed the substrate of the many powerful tribal federations of the Ponto-Danubian region.

[40] From the 9th to the late 8th or early 7th centuries BC, the Agathyrsi occupied the eastern sections of the Pontic Steppe on the northern shores of the Maeotian Sea.

[39] By the time the Agathyrsi were living in the Balkans, they had become a people of mixed Scytho-Thracian[62] origin, composed of a Geto-Thracian population[63] with an Iranic-Scythic ruling class,[61][64][18] as attested by how their kings, such as Agathyrsus and Spargapeithes, were Iranic.

[61][23][18] Herodotus of Halicarnassus claimed that the men of the Agathyrsi had their wives in common so that all of their people would be each other's siblings and members of a single family living together without jealousy or hatred.

[65] The archaeological remains of the Agathyrsi exhibited a unique character due to the absorption of Thracian elements by Iranic incomers,[65] and consist of multiple hundred burials in the form of both cremations and inhumations: the inhumations were themselves buried in simple Scythian-type catacomb tombs, and the grave goods included Scythian-type weapon sets and jewellery from the 6th and 5th centuries BC.