The Greco-Bactrian kingdom was invaded by Seleucid leader Antiochus III.<|im_end|>

 Based on the information provided, the Greco-Bactrian kingdom was invaded by Seleucid leader Antiochus III. This is stated in the text as follows: "In c. 210 BC, the Greco-Bactrian kingdom was invaded by a resurgent Seleucid empire under Antiochus III." Therefore, the answer to the question is: Antiochus III.<|im_end|>

<|im_start|>system
You are an AI assistant. User will you give you a task. Your goal is to complete the task as faithfully as you can. While performing the task think step-by-step and justify your steps.<|im_end|>
<|im_start|>user
The Greek kingdom of Bactria began as a breakaway satrapy of the Seleucid empire, which, because of the size of the empire, had significant freedom from central control. Between 255-246 BCE, the governor of Bactria, Sogdiana and Margiana (most of present-day Afghanistan), one Diodotus, took this process to its logical extreme and declared himself king. Diodotus II, son of Diodotus, was overthrown in about 230 BC by Euthydemus, possibly the satrap of Sogdiana, who then started his own dynasty. In c. 210 BC, the Greco-Bactrian kingdom was invaded by a resurgent Seleucid empire under Antiochus III. While victorious in the field, it seems Antiochus came to realise that there were advantages in the status quo (perhaps sensing that Bactria could not be governed from Syria), and married one of his daughters to Euthydemus's son, thus legitimising the Greco-Bactria dynasty. Soon afterwards the Greco-Bactrian kingdom seems to have expanded, possibly taking advantage of the defeat of the Parthian king Arsaces II by Antiochus.

Answer this question, if possible (if impossible, reply "unanswerable"): The Greco-Bactrian kingdom was invaded by what Seleucid leader?<|im_end|>
<|im_start|>assistant
