In our previous video, we covered the Byzantine – Sasanian War of 602–628. As that conflict and Initial Muslim Invasion are connected, we decided to make the video on the Battle of Yarmouk that took place in 636 between Byzantine Empire (Vahan) and Rashidun Caliphate (Khalid ibn Al Walid). Although it was the Byzantine - Sasanian War that allowed Islamic Invasion to happen, the battle of Yarmouk was decisive for Roman attempts to defend, and its results are still felt in the region.