Korean Buddhism began in the 4th century CE during the Three Kingdoms Period. Centuries after Buddhism originated in India, the Mahayana tradition arrived in China through the Silk Road in the 1st century CE, then entered the Korean peninsula in the 4th century, from where it was transmitted to Japan. In Korea, it was adopted as the state religion of 3 constituent polities of the Three Kingdoms Period, first by the Goguryeo (also known as Goryeo) in 372 CE, by the Silla (Gaya) in 528 CE, and by the Baekje in 552 CE.
Korean Buddhism is distinguished from other forms of Buddhism by its attempt to resolve what its early practitioners saw as inconsistencies within the Mahayana Buddhist traditions that they received from foreign countries. To address this, they developed a new holistic approach to Buddhism that became a distinct form, an approach characteristic of virtually all major Korean thinkers. The resulting variation is called Tongbulgyo ("interpenetrated Buddhism"), a form that sought to harmonize previously arising disputes among scholars (a principle called hwajaeng 和諍).