What was the key reason for Muslim success in conquest?

Answer 1

The key reason in my opinion is that Muslims were not fighting for their personal motivation of having more power, authority, and/or wealth but were fighting for sake of God by defending Islam religion and/or freeing mankind will to be free to chose the faith they are convinced in.

Answer 2

Answer 1
The key is to fight for sake of God to free the will of people and/or to defend Muslims faith, properties, and/or souls and not fighting for gaining power, fame, and/or personal gains.

Answer 2
The Conquests during the days of the Rightly-Guided Caliphs and the Umayyads are not terribly unique or surprising. At that period of time, the mobility of a mounted nomadic army was an incredible advantage over settled peoples who could not coordinate effective defenses. This is because forward positions would be compromised before they could get word to their compatriots in the rearguard. This quite often happened in Muslim conquests.

Additionally, in numerous regions, especially North Africa, the people willingly chose to capitulate without battle and join the Muslims in successive conquest. This allowed for the army to spread further without the attrition to maintain control over the recently conquered territories.

The weakness of settled peoples' defenses to light cavalry is the same reason that the Mongols would be effective conquerors in the 1200s. Settled armies only became more successful than nomadic armies when defensive structures became strong enough to resist the initial attack of light cavalry.

Answer 3

Their common faith