The Tâheriyân of Yemen ruled over vast parts of Yemen during the 9th and 10th centuries AH. During their reign. the Banu Tahir dynasty played an unparalleled role in the culture and civilization of Yemen by supporting science and knowledge, art and architecture. Through prudent policies and the support of local tribes, the Tâheriyân were able to bring Yemen to a state of relative peace and unity. However, during one period of their rule, the Tâheriyân faced a multitude of internal and external problems that ultimately led to the collapse of their government. The main question of this article is how and why the Tâheriyân rule in Yemen was overthrown in the 10th century AH. It appears that a combination of internal and external factors played a crucial role in the overthrow of this government. This research was conducted using a descriptive-analytical method and by using library and documentary historical sources, and It shows that in addition to the internal conflicts of the Tahir family, external factors such as the presence of the Zaydis, Ottoman interventions with the support of the Circassians, and the colonial goals of the Portuguese were among the factors that led to the overthrow of the Tâheriyân rule in Yemen.