Multiple choice What helped the Umayyad caliphs to expand their empire? The Byzantine & Persian empires were weak They used gunpowder to conquer their rivals The Shiites & Sunnis put aside their differences They formed an alliance with the Franks Reveal answer Fill a bubble to check yourself A Correct answer Explanation Decades of intense warfare between the Byzantine and Persian Empires had left both empires economically depleted and militarily weak, allowing the expanding Muslim forces to conquer vast territories with relative ease.