Spread across the northern province of Ninh Binh, the stunning Trang An scenic landscape complex is often called Vietnam's Ha Long Bay On Land.

Covering an area of nearly 2,000 hectares, the Trang An scenic landscape complex is divided into five areas: special reservation area (ancient capital of Hoa Lu), core area, cave area, tourism service areas, and spiritual tourism area of Bai Binh pagoda mountain.

The site boasts 47 historical relics with numerous caves inside stunning limestone karst mountain ranges. The lyric and picturesque landscape of Trang An is a harmonic combination of mountain, valley, and system of lakes.

Trang An features various caves that has undergone impacts of time and weather, decorating with unique shape of stalactites and stalagmites. The system of interconnected cave comprises 30 valleys, each is a amazing picture of mountains, rivers and nature in general.

Floating in a small boat in green and fresh lake, visitors will be amazed by the shade of mountain range reflected in the fresh lake surface, various kinds of wild flowers bloom and dark rock cliff, some goats searching for feed flicker under branch of trees…

The 50 submerged caves act as a gateway leading to other valleys in total span of 20km long. Typical of the caves are Toi (dark) cave which is 315m long and 60m high, Ba giot (Three drops), Seo, Lo, Dot, Dai Linh, Ao trai, and Nau ruou (wine making). They have different features that make Trang An an attractive system of caves. The sparkling of stalactites and stalagmites with unique shapes inside each cave dazzles visitors.

Recent archaeological excavations in the area revealed that lurking behind the magnificent beauty of the area's dramatic mountains and clear blue waters is a long-hidden story that provides exciting clues about the culture of the ancient Vietnamese.

A plethora of archaeological objects, including many limestone artefacts left behind by prehistoric man, have been found at several cave sites in the area.

According to Associate Professor Nguyen Khac Su from the Institute of Archaeology, head of the excavation team at Trang An, these objects offer clear evidence of a long-lasting settlement in the caves of the limestone valleys at an absolutely identifiable date.

"We have been able to discover that the tradition of human cave residency dates back 23,000 years," he says. "The relics and artifacts excavated in Trang An's cave system show that remarkable prehistoric values developed here and passed from generation to generation, becoming a tradition."

In the caves where Su led his excavation, his team discovered an abundance of shell deposits from both fresh water and marine molluscs, some of which were used to make ancient tools and jewellery.

"Similar finds have been made in other northern provinces. Their ages range from 7,000 to 8,000 years old. Jewellery shells were used for both decoration and as currency," Su explains.

The team also uncovered various work tools made from limestone - some relatively fragile but others harder than glass. The haul was complete with the discovery of pottery from the New Stone era.

Samples of natural materials such as pollen, stalactites and soil were taken from the cultural items in order to date the finds as well as shed some light on the geological changes to the region.

Dr Nishimura Masanari, a Japanese archaeologist, has discovered similarities between the Trang An caves and others in the Asian region.

"In Vietnam up to now, few limestone tools have been found, except here at Trang An, while in Malaysia a few similar tools have been discovered. I guess they are from the Hoa Binh culture (12,000-10,000 BC). They indicate that several archaeological caves in Southeast Asia share certain similar features," he says.

More evidence found in the Trang An caves, such as wooden boat- shaped coffins, Han-era tombs and diamond-shaped decorative tiles, suggests that the ancient Vietnamese continued to occupy the area well into the proto and early-historic periods towards the end of the last period of glaciation, when the area's most dramatic geological transformation took place as the area changed into its present shape.

"This is truly a unique discovery, a typical example showing the tradition Vietnamese people have had historically of settling in caves," Su stresses.

Su's team also discovered many bones from buffaloes, cows, stags, and deer. Most surprisingly, bones of rhinos were discovered, which left scientists scratching their heads - the swampy and sunken environment of Trang An does not match their natural habitat. Shells from oysters stuck in the sunken limestone demonstrate rising sea levels and mark the period that humans started coming into contact with the ocean.

The gradual change from freshwater to marine molluscs used as food, culture and ancient tools shows that the increasingly water-dominated environment caused the ancient human inhabitants of the caves to change their lifestyle, diet and technology.

"It can be said that dwellers at Trang An were good at adapting themselves to environmental changes," Su says.

According to the professor, the results of the excavations are contributing significantly to a much wider regional and global reassessment of early human behavioural and cultural diversity while providing some elusive answers to questions about human adaptation in tropical environments.

Not only serving as a cradle of civilisation of ancient Vietnamese, Trang An also used to house the first capital of the Vietnamese feudal and independent state, Hoa Lu, more than 1,000 years ago. Its rugged landscape provided a favourable location for a secure and easily defended citadel.

Even though over 10 centuries have passed and Hoa Lu is no longer the capital, relics have been left behind, including the temples dedicated to Dinh Tien Hoang (968-979), Le Dai Hanh (980-1005) and several one-pillar pagodas from different dynasties. All have helped to build the legend that exists around this ancient culture.

Experts predict that these recent archaeological discoveries mean that Trang An will soon be recognised by UNESCO as a world heritage.

Moreover, Trang An owns diverse ecological system. It is surrounded by primary forests with variety of floral and fauna systems including 310 types of tracheophyta, many kinds of fungi, moss and algae, some rare trees like Dalbergia tonkinensis, Chukrasia tabularis, Burretiodendron hsienmu…, over 30 animals, 50 types of birds, reptiles, especially rare animals like Capricornis sumatraensis, Neofelis nebulosa, white chest gibbon, Buceros bicornis…

Just by discovering the cave system of Trang An scenic landscape complex, visitors will get a deep understanding why it is called "Ha Long Bay on land".