Short answers, pulled from the story.
Nader Shah founded Afsharid Iran after deposing the last Safavid ruler and proclaiming himself Shah in 1736. He was born as Nadr Qoli into a semi-nomadic family of the Afshar tribe in Khorasan and rose from local warlord to ruler of the largest Iranian empire since the Sasanian period.
The Peacock Throne was the imperial throne of the Mughal emperors in Delhi. Nader Shah seized it after defeating the Mughal army at the Battle of Karnal on the 13th of February 1739 and forcing Emperor Muhammad Shah to hand over his royal treasury. Along with the throne, Nader took the Koh-i-Noor and Daria-i-Noor diamonds, with the total haul estimated at as much as seven hundred million rupees.
At its height under Nader Shah, Afsharid Iran encompassed modern-day Iran, the Caucasus, Afghanistan, Uzbekistan, and other parts of Central Asia, as well as parts of Arabia, the Indian subcontinent, Iraq, and Turkey. Nader commanded an army of 375,000 men at his peak.
The plunder seized from the Mughal Empire was so vast that Nader Shah suspended taxation in Iran for three years following his return. Estimates placed the value of the treasures taken from Delhi at as much as seven hundred million rupees, providing enough funds to sustain the state without taxing its population.
The Afsharid dynasty ended in 1796 when Agha Mohammad Khan Qajar, founder of the Qajar dynasty, seized Mashhad and tortured the last Afsharid ruler, Shahrokh, to force him to reveal the location of Nader Shah's hidden treasures. Shahrokh died of his injuries, ending the dynasty. A subsequent revolt by Shahrokh's son Nader Mirza was crushed and Nader Mirza was executed in April 1803.
Nader Shah proposed a modified form of Shia Islam he called Ja'fari, named after the sixth Shia Imam Ja'far al-Sadiq, hoping it would be accepted as a fifth school of Sunni Islam and ease relations with the Ottoman Empire. The Ottomans refused to recognise Ja'farism as a fifth mazhab but did permit Iranian pilgrims to perform the hajj in Mecca.