The Persian Dynasty is an ancient empire that spanned from the 6th century BC to the 7th century AD. It is also known as the Sassanid Empire, which was named after the ruling dynasty of the time, the Sassanids. The Sassanids were a branch of the Pahlavi dynasty, which was founded by Ardashir I in 224 AD. The Pahlavi dynasty was the last imperial dynasty of the Persian Empire and lasted until the Islamic conquest of Persia in 651 AD.