Trajan marched first on Armenia, deposed the Parthian-appointed king (who was afterwards murdered while kept in the custody of Roman troops in an unclear incident, later described by Fronto as a breach of Roman good faith[37]) and annexed it to the Roman Empire as a province, receiving in passing the acknowledgement of Roman hegemony by various tribes in the Caucasus and on the Eastern coast of the Black Sea – a process that kept him busy until the end of 114.[38] At the same time, a Roman column under the legate Lusius Quietus – an outstanding cavalry general[39] who had signaled himself during the Dacian Wars by commanding a unit from his native Mauretania[40] – crossed the Araxes river from Armenia into Media Atropatene and the land of the Mardians (present-day Ghilan).[41] It is possible that Quietus' campaign had as its goal the extending of the newer, more defensible Roman border eastwards towards the Caspian Sea and northwards to the foothills of the Caucasus.[42]