The Islamic Caliphate which had the greatest impact on history is the Abbassid Caliphate which reigned from the 750 C.E. up to 1258 C.E. when they were conquered by Hülegü Khan (brother of Kublai Khan and grandson of Genghis Khan).
cortes
electrisity
Not true it was the greatest impact. It is just part of history. There are many things that have made a greater impact.
WW1
Roman Catholicism.
Fourteenth Amendment
fourteenth amendment
Fourteenth Amendment
slavery
He was the first sultan of Egypt. Not sure of his impact on the feudal system. Question for Egyptian and islamic history.
Majid Fakhry is a renowned scholar who has written various books on Islamic philosophy and theology. Some of his notable works include "A History of Islamic Philosophy," "Islamic Occasionalism," and "Ethical Theories in Islam."
It is probably impossible to argue what had the greatest impact on world history, it did of course have a massive impact and we still see its legacy now, but there are other things that have had an impact that is still with us (from the Roman Empire through to the Cold War). I think this probably counts as either a question that cannot be answered, or one that should be answered simply as "No".