The Byzantine and early Islamic sources for the conquest's decisive battle at Yarmouk disagree sharply on the size of the forces involved, and the conquest itself unfolded as a long sequence of sieges and smaller engagements across Syria and Palestine that the scholarship narrates city by city rather than totals.
What would resolve this A source critical study reconciling the Byzantine and early Islamic casualty traditions for Yarmouk, combined with a historian's accounting of losses across the conquest's separate sieges.
OpenEarly Islamic history, Byzantine history, source criticism.Hugh Kennedy, The Great Arab Conquests: How the Spread of Islam Changed the World We Live In