NOVEMBER 2025
 
 
CONTENT
ANGKOR ASURAS
DEMON-TITANS OF THE KHMER KINGDOM
 
 
At the gates of Angkor, travelers encounter strange figures frozen in stone: powerful faces, tense torsos, hands clutching enormous snakes. These are the asuras, ancient demons from Cambodian mythology, sculpted by the Khmer people with equal parts respect and fear. Born from the depths of time, these beings are not pure evil, but reflections of the primitive force of the world, which opposes, complements, and sometimes saves.

Asuras are a type of demon often found in Indian religions. They are described as entities hungry for power, generally related to the more benevolent gods (devas) in Hinduism. In the Buddhist context, asura can be translated as “titan.”

Asuras pull with all their might on the tail of the serpent Vasuki, while opposite them, the devas hold its head. Together, they spin Mount Meru to churn the primordial sea, seeking to extract the elixir of immortality. The ocean boils, the worlds merge, and from the waves of chaos emerge the treasures of creation. This struggle between gods and demons is not a war, but a vital tension: without the asuras, the world would remain motionless, deprived of breath and movement. The universe is in balance, suspended from the rope of the cosmic serpent.

Angkor sculptors often gave asuras fierce faces, revealing pride and rebellion. Their bulging eyes, arched eyebrows, and conical headdresses distinguish them from the serene gods they face. They are first encountered at the gates of Angkor Thom, lined up along causeways and bridges, pulling Vasuki's tail. The scene is repeated in Angkor Wat galleries, where an immense bas-relief unfolds the same legend with incomparable finesse: more than 90 asuras arch their backs in a rhythmic movement, their knotted torsos and raised headdresses seeming to animate the sanctuary.

At the Bayon, their image becomes more human. Asuras appear in the exterior reliefs mingling with heroes and warriors, as if the boundary between demons and men was blurring under the vision of the creative king Jayavarman VII. At Preah Khan and Ta Prohm temples, they watch over the shadows of lintels and walls overgrown with roots, protecting a world where Buddhism has calmed the fury of incessant fighting.The Kala of Angkor

At Banteay Chhmar, other asuras, carved with great beauty, still reenact the cosmic struggle on the forgotten walls of the temple, their powerful bodies seeming to hold back the stone itself. At Banteay Samré, a long causeway lined with cosmic serpents pulled by demons unfolds in almost untouched silence, reminiscent of scenes from Angkor Wat. The entrances of Ta Som are still marked by eroded statues of asuras and devas facing each other, as if the cosmic struggle was secretly continuing beneath the vegetation.

Banteay Kdei, a peaceful temple with moss-covered walls, has demon heads on its parapets, their sharp features softened by time. Further north, the elegant twin temples of Chau Say Tevoda and Thommanon show figures of asuras entwined with mythical beings on their lintels. The massive, unfinished Ta Keo still has a few asura guardians at its foot, seemingly watching over the ascent to the summit. Near the Bayon, the little-known Preah Pithu complex contains fragments of bas-reliefs where snakes and demons intertwine in the broken stone.

During a journey through Angkor, these figures are everywhere, reminding us of the eternal balance between light and shadow. 

 
THE KARSTIC REGIONS OF VIETNAM
IN THE LAND OF 1,001 MEANDERS
 
 
Vietnam is distinguished by its karst regions, located mainly in the north and center of the country. They form the southern extension of the karsts of Guizhou, Yunnan, and Guangxi, constituting the largest limestone area in the world.

Four hundred million years ago, these regions were covered by warm ocean waters, where marine organisms deposited layers of calcium carbonate and magnesium, creating limestone strata. Pushed above sea level by tectonic movements, the strata rose to form mountains and plateaus. Millions of years of typhoons and slightly acidic rains seeped into cracks, dissolving the brittle parts of the limestone rocks. The water penetrated deeper and deeper, accumulating in underground rivers and basins. Winds and erosion continued to sharpen these heights in capricious ways.

 
The four phases of karst erosion:
1. Soil and other elements are removed from the hills and deposited in the depressions of a pre-karst.
2. Intense karst corrosion beneath the soil cover causes the surface to sink, gradually forming dissimilar areas.
3. Phase of evolution into tropical cones.
4. Erosion of the sides of the karsts and transformation into a plain.
The karsts of the Annamite Range and the Northern Plateau

Covering 40,000 km², this karst complex is the largest in Vietnam. It includes areas of the Annamite Range on the border with Laos (Tay Bac Bo in the north, Bac Trung Bo in the south) and the mountains and plateaus between Hanoi and China (Dong Bac Bo), the latter corresponding to the southern tip of the South China paraplatform.

Karst landscapes develop between 900 and 1,500m above sea level and are characterized by a typical tropical landscape: conical karst, pinnacle karst, and tower karst. Thanks to the uplift phases during the Neogene and Quaternary periods (Himalayan orogeny), the karst relief is characterized by a series of levels marked by peaks, horizontal caves, and flat depressions (sinkholes and poljes).

The limestone formations of Tay Bac Bo (Northwestern Vietnam)

Located in the northwest of North Vietnam, this large karst area is bordered to the southeast by the great valley of the Red River, to the north by the Sino-Vietnamese border, and to the southwest by the Lao-Vietnamese border. The limestone formations appear in the form of parallel strips, 400 km long and 30 to 60 km wide. The most notable formations in Tay Bac Son are:

• The Sin Chai massif, distinguished by a gorge carved out by the Black River.

• The Thuan Chau – Son La massif (or Son La plateau), noted for its aridity, exacerbated by hot winds from Laos during the dry season.Karsts. By Marianne North

• The Moc Chau – Mai Chau massif, marked by red soil poljes ideal for cultivation.

• The Cuc Phuong massif, with its national park, giant Terminalia stellata trees, and prehistoric caves. Near Hanoi, it is Vietnam's first park and reminiscent of what the country was like in historical times when elephants and rhinoceroses roamed these wild spaces.

The limestones of Dong Bac Bo (Northeastern Vietnam)

This karst complex, the second largest in terms of area, is located in the northeast of the country, with the Chinese border to the north, the Red River Valley to the southwest, and the national highway connecting Lang Chanh Province with the city of Lang Son to the southeast. The karsts date from the Upper Carboniferous and Lower Permian periods and are 700 to 1,300m thick. The oolithic limestones are very pure and form conical, pinnacle, and turret formations. The most notable formations are:

• The Bac Ha plateau, distinguished by alternating bands of oolithic limestone, marl beds, and its Hmong population.

• The Dong Van - Quang Ba plateau, located in the far north of Vietnam, is classified as a Geopark. It boasts the Nho Que canyon and massifs, including Mapi Len, Can Ty, and the Phu Tha Ca. The Dong Van karst plateau is the highest in the north of the country; it has a harsh climate during the winter (northeast monsoon) and is mainly populated by White Hmong.

• The Cao Bang – Trung Khanh mountain range is marked by jagged peaks, including Thong Nong, Mo Xat, and Ban Gioc. It also has historical significance (the Bac Bo area, Ho Chi Minh's rear base, the sites of the RC 4 battles – 1947/1950 and the 1979 China war).

• The Na Hang Mountain range, known for its crystallized limestone and Ba Be National Park.

• The Bac Son (Huu Lien) massif, famous for historical sites and rock climbing.
The limestone formations of Bac Truong Bo (Central Vietnam)

This third heavily uplifted limestone area is located in central Vietnam, between Nghe An province in the north and Quang Binh province in the south. It consists of two karst massifs: Con Cuong (Nghe Anh Province) and Ke Bang (Quang Binh Province). Significant formations include:

• The Con Cuong massif, distinguished by whitish limestone bands 40 to 50 km long and the Vuon Quoc and Pu Mat National Parks.

• The Ke Bang (Stone Forest) massif, which covers 2,000 square kilometers and is one of the most remarkable examples of complex karst relief in Southeast Asia (and the world). It is formed by an inextricable network of peaks, caves, sinkholes, and underground networks.

• The Bac Son plateau or formation (known as “1,001 mountains” or “cat ears”) with the plateau at its center is the black hole of limestone massifs, impenetrable and unexplored. In March 2024, Secret Indochina organized an expedition there to identify its southern access point; a second expedition is planned for March 2026, with the aim of reaching the center of the plateau (for information on the 2024 expedition, see the July 7, 2024 newsletter: 
Link)

The karsts on the outskirts of the Red River and Thanh Hoa deltas

The karsts on the outskirts of the Red River and Thanh Hoa deltas are characterized by a typical tropical karst landscape with mogotes no higher than 200 to 300m above sea level. Negative forms dominate and are represented by closed depressions (sinkholes, ouvalas, and poljes) and fluvial-karst plains filled with alluvium and fairly thick red soil. Surface hydrography exists everywhere in the form of streams and temporary or permanent epigeal watercourses. The plains at the base of the hills are favorable for rice cultivation. The most notable formations are:

• The Phu Ly – Ninh Binh massif, distinguished by massive gray and black limestone that alternates with mosaic limestone, enormous alluvial deposits, backfilling due to the alluvial deposits of the Red River, and its nickname, “Halong Bay on land.”

• The Chi Linh - Uong Bi massif, known for its tower karsts and zigzagging depressions.

The Halong Bay maritime karsts


The Halong Bay region is the maritime extension of the mighty limestone massifs that fold from the center of Yunnan under the pressure of the Himalayas. It consists of thousands of islets of various surprising shapes, including cones, peaks, and asymmetrical domes. The area covers approximately 2,500 square kilometers and consists of two specific zones: Halong-Cat Ba in the southeast and Ha Lam-Cam Pha in the northeast, forming sub-bays such as Lan Ha and Bai Tu Long. The limestone dates from the Upper Carboniferous period on a base of marly or oolithic limestone. The main peaks are Nui Nag Tien (445m) and Nui Van Hoa (399m, on Cai Ban island).

The largest island is Cat Ba, which acts as a screen for Halong Bay and stretches 20 km long and ten km wide. On a south-north axis, the main islands have evocative names, such as Surprise, Pyramid, Deer, Doe, Mango, Arena, Jellyfish, Redhead, Table, Boars, Long, Monkeys, Two Chains, Madeleine, Cicadas, Rebel, Big Monkey, Renaud Castle, and Chinese Hat, not far from the Chinese border. Various capes, points, and channels with exotic names dot the bay; the main channels are the Eagle, the Imps, the Lynx, the Rifle, the Jaguar, the Eagle Rock, and the Surprise, with the main points the Crabs, the Mines, Minchao, and the Pirates (west of Cat Ba). Several islands are scored with enormous caves; one of the most famous is Hang Dau Go, the cave of wooden stakes, better known as the Cave of Wonders.

Sources. Presentation of the karst regions of Vietnam. Khang Pham. Journal of Karstology and Physical Speleology, No. 18, 2nd semester 1991, pp. 1-12.

~~


The karst mountains of Vietnam and Laos are part of Secret Indochina's DNA, and they continue to captivate and fascinate us. Adding to their mystery, some of the karsts are still remote or inaccessible, such as the Bac Son plateau, while others are sanctuaries for the country's last primary forests or refuges for little-known ethnic groups. Since its creation, Secret Indochina has conducted various reconnaissance missions in these highlands, the most notable to Coc Xa, Mo Xat, Thong Nong, Sicouty, Phu Tha Ca, Ban Gioc, Huu Lien, Phu Ly - Ninh Binh, and Ke Bang. Since then, we have organized immersions with minority groups, hikes, and treks between levels II and III there.

In another edition, we will discover the karst regions of Laos, as some of them, including Hin Namno, are extensions of the Vietnamese formations...



CAPTIONS

- Banner: Ke Bang range. By the Hin Namno NBCA.
- Image 1: Karsts. By Marianne North.
- Image 2: Karsts of the Northeast. By Jean Despujols.
- Image 3: Karsts of Halong Bay
.

 
Karsts of the Northeast and Hmong youth.
Secret Indochina
        Apsara illustration
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