Transcript Roman-Sassanid Game

Roman-Sassanid Game
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Presenter: Yiyang Zeng
Introduction
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 Wars have been involved in both economic and political
processes during the history of mankind.
 Roman-Sassanid War is a 400-year War between Rome
and Sassanid Persia from 231 A.D. to 631 A.D.
 This war had witnessed the prosperities and downfalls of
Rome and Persia.
 This war can be viewed as a collection of different games.
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Properties of The Games
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 Player 1: Rome
 Player 2: Persia
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Strategy 1: Negotiating for peace and ceasing fire (N)
Strategy 2: Fighting light (FL)
Strategy 3: Fighting hard (FH)
Availability of strategies changed over time.
 Both parties had limited accurate information about another
party’s actions and reactions.
 They did roughly understand the levels of military power of
each other to some extents.
Three Periods of This War
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(1) 231 A.D. to 375 A.D.
Both empires were both exceptionally strong in terms of
military power and they had ideal external
environments.
(2) 376 A.D. to 501 A.D.
Both empires’ powers decreased due to consecutive
wars with each other and their worsened external
environments.
(3) 502 A.D. to 631 A.D.
New leaders, new policies.
-More ambitious
-More aggressive
Period one (231-375)
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 In 224, Ardashir I found the Sassanid Persia Empire.
 In 231, he wrote a letter to Roman Emperor
Alexander Severus, demanding the cessions of
Rome’s Asia territories.
 War broke out inevitably.
 Both players possessed three strategies (N, FL, FH)
Period one (231-375)
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NE: (FL, FL)
PAYOFF: (600, 600)
Period one (231-375)
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Sequential Version: (FL, FL)
Period one (231-375)
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 History tells us both empires successfully managed
to reach the Nash Equilibrium (600, 600)
 During 231 to 375, although both empires had gone
through a large number of battles with each other,
they fought with cautions and the wars were
relatively small compared to those happened later.
 As the result, both empires maintained their power
and prosperities.
Period two (376-501)
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 Both empires suffered decreases in military and economic powers
due to:
(1) Consecutive wars with each other
(2) Worsened external environment:
(a) Rome was under the attacks from Germanic, Alanic, and Hunnic
peoples started from year 376.
(b) Persia was also threatened by Hunnic peoples and then by the
Hephthalites around the same time.
 As the result, both empires were unable to put enough efforts on
attacking each other.
N and FL now become their feasible strategies
The game becomes a coordination game.
Period two (376-501)
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NEs: (N, N) & (FL, FL)
Payoffs: (1000, 1000) & (600, 600)
Period two (376-501)
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Sequential Version: (N, N)
Period two (376-501)
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 History indicates that both empires had successfully
coordinated with each other during most of the period two as
well.
 In year 384 or 387, a peace treaty was signed by Shapur III and
Theodosius I, and both empires stayed in the (N, N) Nash
Equilibrium most of the time from then on with occasional
exceptions.
 In year 421 to 422 and year 440, two minor wars occurred
between the two empires, which can be considered as both
players chose to move to another equilibrium (FL, FL) with
worse payoffs.
Period three (502-631)
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During this period, wars between Rome and Persia intensified dramatically due to their new
leaders and new policies:
(1) Persian King Kavadh I was so ambitious and aggressive that he decided to destroy the then
Byzantine Empire and broke the peace treaty in 502 A.D.
(2) Roman King Justinianus I inherited the throne in 521 A.D. and he was also extremely eager to
regain the power of old Roman Empire.
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Consequently, five intense and long-lasting war broke out (69 out of 129 years)
(1) 528—531 (2) 540—545 (3) 549—562 (4) 571—591 (5) 603—631
+ Along with numerous minor wars began in 502 A.D. between two empires
Only approximately 20 out of 129 years are warless (Yet they were still preparing for wars in
these years: i.e. rebuilt the army, made new weapons, recruited + kidnapped civilians into the army)
Option N can be viewed as “eliminated” from the strategies because both empires opted to do so.
FL and FH become the only strategies for both players during this period
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The game becomes a Prisoner’s Dilemma Game
Period three (502-631)
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NE: ( FL, FL)
Payoff: (600, 600)
Period three (502-631)
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Sequential Version: (FL, FL)
Period three (502-631)
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 History shows that Rome and Persia failed to reach the optimal
equilibrium this time regardless that they had successfully coordinated
with each other in the first two periods.
 In year 631, the war finally ended with great loss:
(1) Their armies sufferred from great casualties
(2) Their financial reserves exhausted
(3) They were never able to regain their power
 Twenty years later, Sassanid Persia was overthrown by the Arabics.
 Later the Byzantine Rome Empire was also destoyed severely by the
Slavs and the Arabics.
Conclusion
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 Both parties in the end failed to coordinate and the game ended in an
internecine way.
 Their failures during period three were due to their irrational behaviors:
(1) They chose to ignore option N
(2) Instead of trying to reach the NE (FL, FL), they both tried to choose fight
hard most of the time
 Policy suggested:
(1) Do not indulge in irrational behaviors (i.e. relentless and exhausting wars)
(2) Acts and reacts after deliberate considerations
References
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 Edward C. Echols, “Herodian of Antioch's History of the Roman Empire.”
1961, <http://www.livius.org/he-hg/herodian/hre605.html>
 J.B. Bury, “The History of Later Roman Empire.” Macmillan & Co., Ltd.,
1923,
<http://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/BU
RLAT/14*.html>
 Anonymous, “Roman-Persian War.” 2010,
<http://baike.baidu.com/view/1433464.htm>
 J.F. Haldon, “Byzantium in the Seventh Century: The Transformation of a
Culture.” Cambridge University Press, 1997,
<http://books.google.com/books/about/Byzantium_in_the_Seventh_Cen
tury.html?id=pSHmT1G_5T0C>