Wikipedia
The Sigynnae were an obscure people of antiquity. They are variously located by ancient authors.
According to Herodotus (v. 9), they dwelt beyond the Danube, and their frontiers extended almost as far as the Eneti on the Adriatic. Their horses (or rather, ponies) were small and flat-nosed with shaggy long hair, five fingers in length. They were not strong enough to bear men on their backs, but when yoked to chariots, they were among the swiftest known, which is the reason why the people of that country preferred that mode of transportation. The people themselves wore a Medic costume, and, according to their own account, were colonists from Media, a claim regarded as doubtful by Herodotus. In Apollonius Rhodius (iv. 320) they inhabit the shores of the Euxine, not far from the mouth of the Danube, while Strabo (xi. p. 520), also speaking of their ponies, and attributing to them Persian customs, places them near the Caspian. They could indeed have been a part of the Iranian expansion, together with the Scythians and Sarmatians migrating west into the Ukraine in the early Iron Age context of the " Thraco-Cimmerian" migrations.
RW Macan (on Herod. v. 9) suggested that the "Medic" connection may be due to a confusion with the Thracian Maedi. In this case the Sigynnae would be a Thracian rather than an Iranian tribe.
According to Herodotus, the Ligyes who lived above Massilia called traders "Sigynnae". According to J. L. Myres, the Sigynnae of Herodotus were "a people widely spread in the Danubic basin in the 5th century BC," and connected with the iron-working culture of Hallstatt, which produced a narrow-bladed throwing spear, the sigynna spear (see notice of "Anthropological Essays" in Classical Review, November 1908).
19th-century historian George Rawlinson speculated that "the Sigynnae retained a better recollection than other European tribes of their migrations westward and Aryan origin", apparently using the term " Aryan" with a meaning somewhere between Indo-Iranian and Indo-European.