the Gates of Alexander and occupied Apamea Ragiana. The locations of these are unknown. Yet the greatest expansion of Parthian power and territory took place during the reign of his brother and successor Mithridates I (r. c. 171–132 BC), whom Katouzian compares to Cyrus the Great (d. 530 BC), founder of the Achaemenid Empire. Relations between Parthia and Greco-Bactria deteriorated after the death of Diodotus II, when Mithridates' forces captured two eparchies of the latter kingdom, then under Eucratides I (r. c. 170–145 BC). Turning his sights on the Seleucid realm, Mithridates 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. This victory was followed by the Parthian conquest of Babylonia in Mesopotamia, where Mithridates had coins minted at Seleucia in 141 BC and held an official investiture ceremony. While Mithridates retired to Hyrcania, his forces subdued the kingdoms of Elymais and Characene and occupied Susa. By this time, Parthian authority extended as far east as the Indus River. Whereas Hecatompylos had served as the first Parthian capital, Mithridates established royal residences at Seleucia, Ecbatana, Ctesiphon and his newly founded city, Mithradatkert (Nisa), where the tombs of the Arsacid kings were built and maintained. Ecbatana became the main summertime residence for the Arsacid royalty. Ctesiphon may not have become the official capital until the reign of Gotarzes I (r. c. 90–80 BC). It became the site of the royal coronation ceremony and the representational city of the Arsacids, according to Brosius. The Seleucids were unable to retaliate immediately as general Diodotus Tryphon led a rebellion at the capital Antioch in 142 BC. However, by 140 BC Demetrius II Nicator was able to launch a counter-invasion against the Parthians in Mesopotamia. Despite early successes, the Seleucids were defeated and Demetrius himself was captured by Parthian forces and taken to Hyrcania. There Mithridates treated his captive with great hospitality; he even married his daughter Rhodogune of Parthia to Demetrius. Antiochus VII Sidetes (r. 138–129 BC), a brother of Demetrius, assumed the Seleucid throne and married the latter's wife Cleopatra Thea. After defeating Diodotus Tryphon, Antiochus initiated a campaign in 130 BC to retake Mesopotamia, now under the rule of Phraates II (r. c. 132–127 BC). The Parthian general Indates was defeated along the Great Zab, followed by a local uprising where the Parthian governor