Sirra[1] (Greek, Ancient (to 1453);: Σίρρα) or (Greek, Ancient (to 1453);: Σέρραι) was an ancient Greek[2] polis (after the 4th century BC) located in Thrace, in the region between the river Strymon and the river Nestos. The city ethnic name was (Greek, Ancient (to 1453);: Σειραίος) or (Greek, Ancient (to 1453);: Σιρραίος) and its territory was called (Greek, Ancient (to 1453);: Σειραίκη γή). Sirra was located in the territory of the Odomantes.
It was founded by Paeonians, expanded by Macedonian kings with immigrants and extended to compromise a vast territory with its Komai. Sirra had participated in a local Pentapolis and perhaps in the earlier sympoliteia. It was the northern limit along with Daneiros of the territory granted to another polis, Philippi by Philip II. Sirra's name has remained relatively unchanged since antiquity, in Serres, Serrai. Sirra was located inland.[3]
The precise location and positive[4] of Ancient Sirra is on the Koulas hill north of the modern city with sparse remains.[5] An improbable identification of Ancient Sirra occurred in the case of (Greek, Ancient (to 1453);: Σίρις της Παιονίας).