The Sassanid Empire existed between 224AD and 640AD, in the land of Persia; a region
which roughly corresponds to around modern day Iraq/Iran area.
The first king, Ardashir I was governer of the Parthian province of Fars, and he founded his dynasty by leading a revolt which brought down the government in Ctesiphon. Ardashir was a descendant of Sassan and it is from his name that the 'Sassanid' name is derived from. The empire grew to be very powerful, and gave the Persians a strong national identity which even outlasted the collapse of the empire and subsequent Arab rule. In part this was helped by Ardashir enforcing religous unity upon the country in the form of Zoroastrianism.
Almost from the founding of the empire, the Sassanids fought the Romans to the west, which continued with only short periods of peace over the next 400 years. They were damn good opponents to the Romans as well; Shapur I, (Ardashir's son) even managed to capture the emperor Valerian.
The Strategikon of Maurice (ca. 570) had this to say about the Sassinid army tactics; they have
"an orderly approach", "battle with calmness and determination," and "not attack in a disorderly fashion."
As at the time most armies still organised themselves along tribal lines, perhaps it can be seen
why the Sassanids had so much success and could compete with the Roman war machine.
Large armies were often deployed in 5 sections, the main battle line, a reinforcing line, a line of reserves, two cavalry wings and a small reserve force of special
forces; The Immortals and elite cavalry. The cavalry were a particulary important feature of the army,
in fact the Persians did field armies of all cavalry, both lightly armoured and more heavily armoured
lancers; sometimes even the horses were armoured. Use of the bow was also made on horseback.
As the Roman empire dwindled, the Sassanid capital, Ctesiphon grew in magnificence and influence, producing amazing works of art in metalwork, architecture,
sculpture, and textiles. (See www.hp.uab.edu/image_archive/ugp/ for some examples of art works.)
The state religon was Zoroastrianism, and persecution of Christians eventually led to wars with Byzantium (the name given to the eastern Roman empire.)
The reign of Anushirvan the Just a.k.a Khusraw I between 590 and 628 stands out in particular, he
instigated sweeping reforms that helped keep stability in the country for years to come. By improving
the efficiency in the tax system he was able to afford to pay the soldiers in his army a wage and equip
them very well. This in turn decreased the power of noble's private armies, and helped stamp out
internecine struggles before they could start. This tax model was later employed by the Arab
caliphate in Baghdad.
The rapid fall of the empire after 400 years has been attributed in part to the attitude both the Sassanids
and the Byzantine Romans had; both of them felt themselves to be superior to all other countries. The
continual struggle between themselves for mastery lead them to ignore the threat of their neighbours; as
they weakened themselves with centuries of costly wars and campaigns, so their enemies power grew.
Also in the last decades of the empire stagnation had set in, the provinces allegiance to the central
government weakened and infighting led to 7 Kings in about 15 years. When the Arabs finally invaded,
they were able to win some of the provinces by saying in essence "We'll lower your taxes, and you don't even have
to convert to Islam!".
In 638 the Arabs had captured the capital city, forcing Yezdigird III to flee, and by 642 the Persian
army had all but been destroyed, giving them control over the whole Iranian plateau. In 651, having been in exile for nearly 10 years in the eastern mountains, struggling to muster an army
to counter-attack, (he even sought friendship with the Chinese Emperor Tai Tsung) Yezdegird III was assasinated by his own men.
Chronology Of The Sassanid Empire
226-240: Reign of Ardashir I
226-227: Revolts aginst the Parthian Empire
229-232: War with Rome
--Zoroastrianism is revived as official religion.
--The collection of texts known as the Zend Avesta is assembled.
241-271: Reign of Shapur I
241-244: First War with Rome.
258-260: Second War with Rome.
260: Defeat and capture of Roman Emperor Valerian
215-271: Mani, founder of Manicheanism.
271-301: A period of dynastic struggles
272-273: Reign of Hormizd I
273-276: Reign of Bahram I (NB Bahram is also rendered as Varahran)
276-293: Reign of Bahram II
293-293: Reign of Bahram III
293-302: Reign of Nerseh or Narses defeated by the Romans in 298 under emperor Galerius, Ctesiphon taken.
302-309: Reign of Hormizd II
309-379: Reign of Shapur II
379-383: Reign of Ardashir II
383-388: Reign of Shapur III
388-399: Reign of Bahram IV
399-420: Reign of Yezdegird the Wicked
409: Christians are permitted to publically worship
and to build churches.
416-420: Persecution of the Sassanid Christians as Yezdigird
revokes his earlier order.
420-438: Reign of Bahram V.
420-422: War with Rome.
424: Council of Dad-Ishu declares the Eastern Church independent
438-457: Reign of Yezdegird II
457-459: Reign of Hormizd III
459-484: Reign of Peroz
483: Edict of Toleration granted to Christians
484-488: Reign of Valash
484-520: White Huns over-run the empire and install puppet as kings, until in 520 some Turkish
tribes from Asia aid the Persians and overthrow the Huns.
488-496: Reign of Kavadh I
491: Armenian Church repudiates the Council of Chalcedon
--Nestorian Christianity becomes dominant Christian sect
in Sassinid Empire
496-498: Reign of Zamasp
498-531: Reign of Kavadh I
531-579: Reign of Anushirvan the Just a.k.a Khusraw I
533: Treaty of Endless Peace with Rome.
540-562: War with Rome.
579-590: Reign of Hormizd IV
590-590: Reign Of Bahram VI Chobin
590-628: Reign of Khusraw II Parviz
603-610: War with Rome
610: Arabs defeat a Sassanid army at Dhu-Qar.
614: Capture of Jerusalem and the 'True Cross'
619: Conquest of Eygpt
610-620: War with Rome continued.
(in 608, 615, 627 Khusraw's armies reach Chalcedon
626: Siege of Constantinople.
627: Roman Emperor Heraclius invades Assyria and
Mesopotamia. Persians lose decisive battle of Nineveh
628-628: Reign of Kavadh II
628-629: Reign of Ardashir III
629-629: Reign of Shahrvaraz
629-630: Reign of Borandukht
630-632: Reign of Hormizd V
632-642: Reign of Yezdigird III (in exile until 651)
633: Muslims invade Iraq.
642: Persian army destroyed at Nehawand.
Note a lot of the above spellings seem to derive from onomatopoeic translations, and so differ quite widely. If any historians know what the definitive spellings should be, please /msg me!