Complex sentence: The Nhi Thanh Cave, about 700 m away from the Tam Thanh Cave, was discovered in the 18th century by Ngo Thin Sy, military commander of the Lạng Sơn garrison, whose poems have been inscribed at the entrance to the cave.
Split into simpler sentences: The Nhi Thanh Cave, about 700 m away from and Tam Thanh Cave, were discovered in the 18th century by Ngo Thin Sy, a military commander at the Lạng Sơn garrison. His poems have been inscribed at the entrance to the cave.