Our new animated historical documentary series on the Byzantine-Bulgarian Wars will start with the story of the battle of Pliska or battle of Varbitsa pass between the Eastern Roman emperor Nikephoros I and the khan of the First Bulgarian Empire Krum. The story starts right after our video on the Umayyad Caliphate's siege of Constantinople in 717-718, during which the allied Byzantine-Bulgar forces stopped the Muslim expansion in the region.