Short answers, pulled from the story.
Human settlement at Erbil dates back to the 5th millennium BC during the Neolithic period. The city has been continuously inhabited since ancient times with evidence of occupation on the citadel mound from that same era.
The Assyrians conquered Erbil beginning in the late 2nd millennium BC. Subsequent empires including the Median Empire, Achaemenid Empire, Macedonian Empire, Seleucid Empire, Parthian Empire, Roman Assyria, and Sasanian Empire all held control over the region.
The Mongols attacked Arbil for the first time in 1237 and returned after a six-month siege following the fall of Baghdad in 1258. Sustained persecutions of Christians began in earnest in 1295 under Oïrat amir Nauruz leading to massacres of defenders in 1310.
Erbil Citadel was inscribed on the World Heritage List on the 21st of June 2014. The High Commission for Erbil Citadel Revitalization established in 2007 evicted all inhabitants except one family as part of a large restoration project.
The city is predominantly Kurdish with minorities including local Turkmen Chaldeans Assyrians and Arabs. In 2020 an estimated 450,000 refugees had settled in the Erbil metropolitan area since 2003 while around 230,000 internally displaced persons remain.