What is the Silla Dynasty?

The Silla Dynasty (57 BC–935 AD) in ancient Korea was arguably one of the longest lasting dynasties on earth. 
In ancient Korea, the Silla kingdom (along with the Baekje and Goguryeo kingdom) formed what was called the Three Kingdoms. Silla was known for its centralized system of government and its strict adherence to a hierarchical social system. The kingdom was said to have been founded by King Hyeokgeose. 
The three kingdoms fought against each other for control of the Korean peninsula. During a period of upheaval, Baekje and Goguryeo formed an alliance for the sole purpose of conquering Silla. Meanwhile, all three kingdoms tried to broker alliances with the Japanese and Chinese in order to defeat each other.
The Chinese Tang dynasty eventually chose to ally itself with Silla. The Tang-Silla alliance crushed the Baekje and Goguryeo kingdoms. However, Silla did not let matters rest. With Goguryeo and Baekje vanquished, Silla trained its sights on the Tang dynasty. Silla finally won control of Korea when it defeated China in the battles of Kibolpo and Maesosong. For more information, please refer to the two links below. 
https://www.ancient.eu/disambiguation/Three_Kingdoms_Period/