|Second Sassanid Empire|
The Empire in 1710, two years before the split
Orthodox Church, Islam, Hinduism (minor)
|-||710–726 (first)||Khosrau I|
|-||1671–1712 (last)||Peroz VII|
|-||Formation||5 May 710|
|-||Split||18 October 1712|
The Second Sassanid (or Sasanian) Empire, also known as the Neo-Sassanid Empire, was a Persian-speaking empire that existed for over one thousand years, from 710, when shah Khosrau I founded a new realm after the death of his father Bahram VII (the last ruler of the Sassanid Empire) until 1712, when the empire split in two, forming the modern nations of West Persia and East Persia.
Khosrau I, also known as Khosrau the Great, started a new mixed dynasty by marrying a Byzantine princess and introduced several important reforms during his reign of sixteen years, such as lifting the ban on Islam and Christianity started by his predecessors. The new ruler promoted religious tolerance and the co-existence of several faiths and cultures within the empire, values that persisted for centuries.
In the 9th century, the neo-Sassanid dynasty was supplanted, but the empire retained its name. Around 1050, new rulers abandoned Khosrau's original ideas of tolerance and installed a strictly enforced Zoroastrian theocracy, which lasted until the mid-14th century, when new Shahs went back to the old ideals of tolerance and peace, improving the relations with European nations. In 1502, in a diplomatic tactic of ensuring economical opportunities in Europe, the Sassanids conquered the aggressive Turkic tribes of Central Asia, ending the long-lasting Christian-Zoroastrian conflicts.
In the 17th century, notable cultural and administrative differences existed between the western and eastern portions of the empire, the first being more traditional and closer to Byzantium and the European world and the latter being much more autonomous and closer to the Indian states. Furthermore, ruling over such a vast territory was expensive and exhaustive. For those reasons, in 1712, the Second Sassanid Empire came to an end splitting in two. Although Isfahan served as the capital through much of the empire's existence, the new nations chose other cities as their capitals: Tehran for West Persia and Kabul for East Persia.