Complex sentence: After defeating the Greco-Bactrian Kingdom in the east, Mithridates then focused on the Seleucid realm, he invaded Media and occupied Ecbatana in 148 or 147 BC; the region had been destabilized by a recent Seleucid suppression of a rebellion there led by Timarchus.
Split into simpler sentences: After defeating the Greco-Bactrian Kingdom in the east, Mithridates then focused on the Seleucid realm. He invaded Media and occupied Ecbatana in 148 or 147 BC; the region had been destabilized by a recent Seleucid suppression of a rebellion there led by Timarchus.