Thanks to its many geographical advantages, what is now Hoi An began its development under the Late Sa Huynh culture about 3,000 years ago. Archaeological studies of relics such as tombs, and unearthed stone, ceramic, glass and metal tools show a splendid Sa Huynh culture had existed over a long period in this area.
In particular, the discovery of two types of brass coins from China under the Han Dynasty, objects similar to that of the Dong Son-Oc Eo cultures, indicate that foreign trade was first established in Hoi An at the start of the 1st century. And, the inhabitants of the Sa Huynh culture had made Hoi An an international port for the Cham and the Viet under the Dai Viet – Dai Nam epoch.

Check the tours to come to visit Hoi An:
Flavor of Vietnam: Hanoi to Hoi An
Vietnam itinerary 10 days from Hanoi to Hoi An
HISTORY OF HOI AN CITY:
Under the Cham Dynasties (9th-10th century), Hoi An, or Lam Ap city as it was called at the time, already was a developed seaport harboring merchant ships from Arabia, Persia, and China.
Many old documents indicate the Cham port of Lam Ap Had played an important role in the building of Tra Kieu capital city and the My Son towers. Such vestiges as the Cham ruins, Cham wells, Cham statues and the unearthed pieces of Chinese, Dai Viet, and Middle East potteries dated from the 2nd to 14th century indicate that Lam Ap city (under the Cham or Hoi An (under the Dai Viet) had been a busy commercial port.
With the introduction of the Silk Road and the ceramics trade by sea routes, merchant ships from China, Japan, India, Siam (Thailand), Portugal, England, and France flocked to Hoi An. In this golden era, (16th to 19th century) Hoi An had become one of the busiest international commercial ports in Vietnam and Southeast Asia, an important economic center under the Nguyen’s Lords of southern Vietnam at that time.
The commercial port of Hoi An continued to flourish until the early 19th century when the Cai River became inaccessible to vessels to harbor because of sediments. Its historical role was taken over by the new port of Da Nang in the industrial epoch. Yet, Hoi An continued to be a trading center from the beginning of the 20th century until 1945.
Thanks to this change of roles, Hoi An has avoided all the transformations that could alter a Middle-Age city and make it a modern city and the old city structures could be preserved.
Scientists say the old city of Hoi An is a model of southeast Asian seaports in the 15th to 19th centuries Because of the many influences, Hoi An and is a land of many traditions, both historical and cultural, and has crystallized through its many evolutions into the well preserved old port city it is today.
On December 4, 1999, the United Nations Educational, Scientific, and Cultural Organization (UNESCO) recognized Hoi An as a World Heritage.
ARCHITECTURE OF HOI AN ANCIENT CITY:
Statistical surveys show that the ancient city of Hoi An has 1,360 vestiges which are grouped into 11 categories: 1,106 old houses, 11 old wells, 38 forefathers, temples, 19 pagodas, 43 temples, 23 communal shrines, 1 bridge, 5 assembly halls, and 44 ancient tombs. The Old Town alone has 1,107 vestiges.
Many old structures in Hoi An reflect rare traditional architecture. Almost all shop still utilizes thin wooden boards for the facade,(a kind of door common to ancient Hoi An architecture). The boards are removed to open the shop, showing the open space, and put back up when the shop is closed.
Most of the roofs are covered with curved tiles, with the smaller tiles placed on the edges of two adjacent larger ones. Tiled roofs can be densely covered and pasted together, with 400 tiles per square meter, but normally they are covered with one layer, about 150 tiles per square meter. In the rainy season, grasses, mosses, and lichens develop on the roof, giving an antique appearance to the city.
Many houses in Hoi An old town have two “door” eyes” or round-shaped mirrors to represent the “eyes” of the house. According to a Taoist belief, houses are also living creatures, so they must have eyes to see. Interesting is the fact that these eyes are carved in an eight-sign (or signs within signs) patterns to ward off bad luck. Some houses have the “door eyes” carved with the figures of five bats (representing “Ngu Phuc” or Five Happiness) gathering around the letter “Tho” (Longevity). In some “door eyes”, the eight signs are linen leaves pointing toward the center of the “ying and yang” figure, Many researchers have studied the designs of “door eyes” to examine the integration of different religions by traders in ancient Hoi An.

Situated in the low basin of the Thu Bon River, Hoi An is almost inundated by the rising water for several months during the rainy season. Especially in areas by the riverbank water may sometimes rise to the rooftops, but usually, rises to one meter or more above ground. In feudal times, peasants were not allowed to build their houses taller than the Lord and mandarins, residences. All houses in Hoi An have an attic for their occupants to escape floods, but the houses of royalty and prominent government officials were better able to avoid damage. The biggest flood recorded in Hoi An was in 1964 when all houses were submerged by flood water.

Floods cause damage but are also advantageous to the city because floodwater deposits silt useful to farmers and kill worms harmful to wooden structures.
Thus, many people say “Hoi An without floods is no longer Hoi An”. In fact, many tourists enjoy riding boats in the inundated streets of Hoi An during the rainy season.
Though some old structures in Hoi An have deteriorated by time, war and natural calamities, many still preserve their original state from the last century. Local authorities and the people of Hoi An are striving to restore and preserve the peculiarities of this old city.