Parthian Dynasty

Parthian Dynasty

By the first half of the 3rd century BC, the Parni, a nomadic Aryan tribe from the steppes of Central Asia, had migrated into the Achaemenid/Seljuk satrapy of Parthia . In 238 BC, a tribal leader of the Parni named Arsaces overthrew the Seljuk satrap of Parthia and began the dynasty of the Arsacid Parthians in the district of Astavene.
According to Iranvisitor website, at around 235 BC, the brother of Arsaces, Tiridates (meaning “great archer“ in the Parthian language) led an army to the south and conquered the rest of Parthia . Seljuk II attempted to check the Parthian advance but he was defeated and Hyrcania also fell.
Seljuk Decline
The young Parthian nation paid tribute to the Seljuk kings until the 2nd century BC when Seljuk power began to fade. The provinces of the Seljuk Empire gradually began to fall to the Parthians and in 139 BC, Mithradates I, who reigned during 138-171 BC, captured Seljuk King Demetrius Nicator, who was held captive for ten years while the Parthians conquered Mesopotamia and Media.
In the west, the Parthians were pitted against the Roman Empire and they proved to be a thorn in their side for over three centuries. Parthian cataphracts (heavily armored cavalry) backed by brigades of mounted archers were well suited to disrupting the tight organization of Roman foot soldiers and defeat them. This had a precedent in the army of 40,000 under Crassus in 53 BC, which gave the Romans much to think about and forced many changes in the Roman war tactics.
Expansion
By 129 BC, Parthian rule extended as far as the banks of the Tigris where they established a winter encampment at Tisfun directly opposite Seljuk, the Hellenisitic capital of Western Asia .
They did not take the city, however, because of its wealth and trade potentials. During the summer, the Parthians would retire from the sun-baked Mesopotamian plain to the ancient Persian capitals of Susa and Ecbatana .
With an empire spreading from Armenia to India , king Mithradates II, who reigned during 123-88 BC, consolidated Parthian power and wealth. He established caravan routes across his united realm, linking trade routes already existing to the east and west of Iran .
Silk Road trade spanning the Asian continent from China to the Mediterranean served to enrich the empire.
Downfall
However, it was the feudal organization of the Parthian Empire, once the source of its great strength that eventually led to its downfall. The regional nobilities that had grown both in wealth and military power through concessions granted to them for their constant campaigning against the Romans and other enemies gradually became less inclined to obey central authority.
Their refusal to pay levies and, more importantly, to raise armies for the king led to disorganization and fragmentation. Arguments over succession to the throne sowed further disarray.
The Romans were quick to take advantage of these internal weaknesses. Since they were also familiar with Parthian tactics, the Romans managed to capture Tisfun in 116 and 198 AD. And that marked the beginning of the Parthian fall.