What if the Battle of Qadisiyyah Had a Different Result
The battle of Qadisiyyah was fought in 636 CE from November 1-4. The battle is not known well in Western history but it had major implications for the West and much of the globe. This was a battle where the Arab armies, newly converted to Islam, were able to defeat the Sasanid Persian Empire. The result was the conquest of what is now Iraq and eventually Persia, allowing the new Islamic Empire to emerge in the Middle East and, eventually, expand to other areas.
The Historical Circumstances
In 636 CE, there were two major universal religions, which were Christianity and Zoroastrianism. These faiths were supported by the two major superpowers of the Middle East, which were the Byzanitine and Sasanian Empires. Both these powers seemed invincible and held much great wealth. However, by the early 7th century CE, major wars across the Middle East devastated much of the region and led to both these empires to deplete their resources.
In 636, Caliph Umar had re-invaded Iraq, after a previous Muslim army was defeated and removed from the region. The battle was mostly fought by a relatively inexperienced Arab army against the better trained and equipped Persians. However, a key turning point was reinforcements to the Arabs, who were much more professional soldiers, arrived at the battle of Qadisiyyah on the second day. These numbered about 5000 and proved to be the difference in allowing the Arabs to breakthrough the Persian main line, causing them to routed and forcing the main Persian force to retreat.