Atropates

Atropates (c. 370 BC – after 321 BC) was a Persian nobleman who served Darius III and then Alexander III of Macedon. He made an independent kingdom. A dynasty was named after him. Diodorus Siculus calls him 'Atrapes'. Quintus Curtius wrongly names him 'Arsaces'.
Biography.
At the end of the Achaemenid Empire, Atropates was governor ("satrap") of the Achaemenid province of Media. In the Battle of Gaugamela (October 331 BCE) between Darius and Alexander, Atropates was in charge of the Achaemenid troops of Media.
When Darius lost he went to the Median capital of Ecbatana. Atropates helped him. Darius tried to get a new army but could not. He left Ecbatana in June 330 BCE. After Darius' death a month later at the hands of Bessus, Atropates surrendered to Alexander. Alexander first chose Oxydates as satrap of Media. In 328-327 BCE Alexander did not trust in Oxydates' loyalty. Atropates was made satrap again. In 325-324, Atropates gave Baryaxes (a rebel of the area) to Alexander. Alexander thought highly of Atropates.
Alexander died on June 10, 323 BCE. Atropates' new son-in-law Perdiccas was named regent of Alexander's half-brother Philip III. After the "Partition of Babylon" in 323 BCE, Media was divided into two parts. The greater portion in the south-east was governed by Peithon, a general of Perdiccas. The smaller portion in the north west was given to Atropates. At some point, Atropates made his part of Media an independent kingdom. His son-in-law Perdiccas was murdered by Peithon in the summer of 320 BCE.
Legacy.
The dynasty Atropates made would rule the kingdom for several centuries. They became vassals of the Seleucids, then as vassals of the Arsacids.
The area of Atropates' kingdom was known to the Greeks as "Media Atropatene" after Atropates. Then as simply "Atropatene". The Arsacids called it 'Aturpatakan' in Parthian, as did also the Sassanids. Eventually Middle Iranian 'Aturpatakan' became 'Azerbaijan'. This is where the Republic of Azerbaijan and the Iranian province of Azerbaijan get their name.