Arsacid Dynasty
In the epigraphs of Bistoon and Persepolis, Sistan is mentioned as one of the eastern territories of Darius the Great. The name Sistan, as mentioned above, is derived from Saka (also sometimes "Saga", or "Sagastan"), a Central Asian tribe that had taken control over this area in the year 128 BC. During the Arsacid Dynasty (248 BC to 224 AD), the province became the seat of Suren-Pahlav Clan. From the Sassanid period till the early Islamic period, Sistan flourished considerably.