Caliph Al-Mu'tasim was the ninth Abbasid caliph, ruling from 833 to 842 CE. He is known for his military campaigns and efforts to expand the Abbasid Empire. Al-Mu'tasim established a standing army, known as the ghulam army, which consisted of slave soldiers who were loyal to him. During his reign, Al-Mu'tasim also focused on cultural and architectural developments. He founded the city of Samarra, which became a significant political and cultural center. His rule is marked by both military achievements and advancements in art and architecture, contributing to the legacy of the Abbasid period.