 The military operations of Shapur's father Ardashir I had led to the local Kushan and Saka kings offering tribute, and satisfied by this show of submission, Ardashir seems to have refrained from occupying their territories.Al-Tabari alleges he rebuilt the ancient city of Zrang in Sakastan (the land of the Sakas, Sistan), but the only early Sasanian period founding of a new settlement in the East of which we are certain is the building by Shapur I of Nishapur - “Beautifull (city built) by Shapur” - in Dihistan (former Parthia, apparently lost by the Parthians to the Kushans).Soon after the death of his father in 241 CE, Shapur felt the need to cut short the campaign they had started in Roman Syria, and reassert Sasanian authority in the East, perhaps because the Kushan and Saka kings were lax in abiding to their tributary status.