Short answers, pulled from the story.
The Parthian Empire existed from 247 BC to 224 AD, a span of roughly 471 years. It was founded by Arsaces I of the Parni tribe and ended when Ardashir I defeated and killed the last Arsacid ruler, Artabanus IV, at the Battle of Hormozdgan on the 28th of April 224 AD.
The Parthian Empire was founded by Arsaces I, who was chieftain of the Parni, a nomadic Central Asian tribe of Iranian peoples within the confederation of the Dahae. The Parni likely spoke an eastern Iranian language and were not originally from Parthia itself, a northeastern province they conquered from a rebellious Seleucid satrap named Andragoras.
At the Battle of Carrhae in 53 BC, the Parthian commander Surena used approximately 9,000 horse archers and 1,000 cataphracts against Crassus' seven Roman legions. A baggage train of about 1,000 camels kept the horse archers continuously supplied with arrows, and they employed the Parthian shot tactic, feigning retreat then turning to shoot at exposed Roman infantry. Some 20,000 Romans were killed and approximately 10,000 were captured.
The Parthian Empire sat between the Roman Empire in the Mediterranean and the Han dynasty of China, and it was enriched by taxing Eurasian caravans. Silk was the most prized commodity moving westward; the Han Empire sent a formal trade delegation to the court of Mithridates II in 121 BC. Parthian goods sold to Roman merchants included iron from India, spices, and fine leather, while Sogdian merchants served as the primary trade middlemen.
The Parthians left far fewer written records than the Achaemenid or Sasanian empires that preceded and followed them. Surviving indigenous sources include scattered cuneiform tablets, fragmentary ostraca, rock inscriptions, drachma coins, and some parchment documents. Most detailed accounts of Parthian history were written by Greek, Roman, and Chinese observers, all of whom wrote from an outsider perspective and focused primarily on military and political events.
The Parthian Empire ended on the 28th of April 224 AD when Ardashir I, the local Iranian ruler of Persis from Istakhr, defeated and killed the last Arsacid ruler Artabanus IV at the Battle of Hormozdgan. Ardashir then established the Sasanian Empire, which ruled Iran and much of the Near East until the Muslim conquests of the 7th century AD.