when did he reign?
Between 94 and 93 BC
Antiochus XI Epiphanes
Antiochus XI Epiphanes Philadelphus (; died 93 BC) was a Seleucid monarch who reigned as King of Syria between 94 and 93 BC, during the Hellenistic period. 
who is antiochus xi epiphanes? A Seleucid monarch who reigned as King of Syria
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Antiochus XI Epiphanes [SEP] Introduction
Antiochus XI Epiphanes Philadelphus (; died 93 BC) was a Seleucid monarch who reigned as King of Syria between 94 and 93 BC, during the Hellenistic period. He was the son of AntiochusVIII and his wife Tryphaena. AntiochusXI's early life was a time of constant civil war between his father and his uncle AntiochusIX. The conflict ended with the assassination of AntiochusVIII, followed by the establishment of AntiochusIX in Antioch, the capital of Syria. AntiochusVIII's eldest son SeleucusVI, in control of western Cilicia, marched against his uncle and had him killed, taking Antioch for himself, only to be expelled from it and driven to his death in 94 BC by AntiochusIX's son AntiochusX.