Final answer:
The Rurik Dynasty died out due to infighting among descendants, Mongol invasion, and the Black Death.
Step-by-step explanation:
The Rurik Dynasty, also known as the Rurikids, eventually died out primarily due to a combination of factors. One important reason for their decline was the perpetual infighting among the descendants of Rurik, the founder of the dynasty. This led to a civil war and the division of the empire into separate realms. Additionally, the Rurik Dynasty faced other challenges such as the Mongol invasion and the Black Death, which resulted in population decline and political instability.