Approaching the Hoành Sơn Pass at Dusk - Part 1: A Great Milestone in the Journey of Territorial Expansion

The Hoành Sơn Pass, known historically as Hoành Sơn Quan, is presented not merely as a geographical feature but as a profound symbol of Vietnam's historical expansion. The author describes an overwhelming emotional connection to this location, considering it the starting point of a monumental era in Vietnamese history – the age of southward territorial expansion.

This mountain range, a spur of the Trường Sơn Bắc mountains, juts dramatically into the East Sea. For millions of years, it has stood as a formidable natural entity, creating a stark division between two distinct climate zones and historical regions. Its rugged granite structure, stretching approximately 50 kilometers, has historically acted as a critical bottleneck along the vital North-South route, constricting the narrow coastal plains of Central Vietnam.

The pass itself, standing at 256 meters, separates the northern province of Hà Tĩnh from the southern province of Quảng Trị, marking a climatic boundary as well. Ancient texts, such as Ô châu cận lục, describe the formidable nature of this barrier: "The mountain range from Tổ Sơn leads here, with the posture of a coiling dragon and a sitting tiger, high hills form successive barriers, stretching to the sea, with sheer cliffs ten thousand fathoms high, like a great wall guarding the southern region."

Beyond its role as a geographical and climatic divider, the Hoành Sơn range holds deep historical significance related to early border fortifications. Researchers have explored the mountains in search of remnants of the Lâm Ấp or Hoàn Vương ramparts, believed to have marked the ancient Việt-Chăm border. Despite facing considerable difficulties and dangers, these researchers have uncovered vestiges and sections of stone walls amidst the dense jungle, providing tangible links to Vietnam's early history of territorial demarcation and conflict.

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The mountain range from Tổ Sơn leads here, with the posture of a coiling dragon and a sitting tiger, high hills form successive barriers, stretching to the sea, with sheer cliffs ten thousand fathoms high, like a great wall guarding the southern region.