Original: Originally, it was the only connection between North and South Korea but that changed in 2007 when a Korail train crossed the DMZ to the North on the new Donghae Bukbu Line built on the east coast of Korea.
Simplified: Originally, it was the only connection between North and South Korea. In 2007 a Korail train crossed the DMZ to the North on the new Donghae Bukbu Line built on the east coast of Korea.