A casting mould for cauldrons discovered during excavations in 2004 at Takht-i Sangin, Kurgan-Tiube district (Khatlon district), Tadzhikistan, is published. The cauldron was meant to bear a dedicatory inscription to Oxos, written in Greek. The cauldron may be dated by its context to the late 2nd century BC. The inscription has major implications for the beginning of Bactrian script. Metallurgical analyses, the context, the mould itself and some analogous metal artifacts allow the authors to discuss interaction of the Greco-Bactrian, Scytho-Saka and Chinese cultures of the period in the field of copper-based metallurgy (bronze casting). The fact that several such cauldrons were cast for the temple at Takht-i Sangin in a workshop of Greek type casts a new light on the cult of Oxos, the local river god.