The dam of Marib was built in the middle of the 1st millennium BC. Long before dams and flood embankments in Wadi Dhanah been demonstrated that for the 3rd millennium BC, built and operated at the Sabaean capital Ma'rib. The dam was considered the greatest technical structure of antiquity is the miracle of Arabia. The dam is part of the coat of arms of the Republic of Yemen.
Since the Yemeni highlands and the edge of Ramlat it - Sayhad are low in rainfall, in the 3rd millennium were BC dams in Wadi Dhanah built like other places in South Arabia to save the seasonally flowing water of Sayl - flood. The most recent and most important plant was built by the Sabaean Mukarriben Sumuhu'ali Yanuf II and Yitha'amar Bayyin II. It reached a length of 680 m and 20 m height and allowed the irrigation of approximately 9,600 ha of farmland in the 21 km long and 8 km wide oasis. In order for the population to be served by Marib with food.
On the dating of the dam, there are different opinions. Hermann v.Wissmann it sets the end of the 6th century BC onwards, KA Kitchen, however, in the first half of the 4th century BC.
The dam consisted of an earth dam, the clear passage through the valley of the Wadi and is no longer available today, and two lock structures on the northern and southern slopes. These structures, which are partially preserved, have dimensions of 145 m length, 50 m width and 13 m in height and consist of three pillars with two diffusers. The walls were partially destroyed in past centuries, because the stones were used for other buildings. They are dug in the time of archaeologists, rebuilt and will be collected at the Unesco Heritage Site.
The locks were used for irrigation; the water was passed only after a primary channel and subsequent distribution channels to the fields in the oasis. The locks also had brick overflows ( a spillway ), where excess water could be safely discharged into the stilling basin.
Because of the mud deposits of one centimeter per year of boulevard and all buildings often had to be increased. They were repeatedly being demolished and rebuilt. Even were often repairs after dam failures due to high water needed.
With the decline of trade on the Incense Road since the Christian era, an increasing neglect of the dam began. This led since the 4th century to several dam failures. King Sharahbil Yafur has let the dam, according to reports in the year 449 AD repair, but 450 he was again damaged by floods. The dam was again repaired. The last time, in the year 542, during the rule of the viceroy Abraha, a Christian ruler of Abyssinia, from a larger fraction and of the restoration of the dam reported. The last known inscription that refers to the dam, comes from this year ( according to other sources of 548 ). It is reported that the Viceroy had ordered repairs and large quantities had ordered supplies for the many workers, including 200,000 sheep and goats, 50,000 sacks of flour and 26,000 boxes of dates. Apparently, the reconstruction was carried out promptly.
Since the decline of the incense trade but the population lost its economic basis, also lost the dam by deducting the people its meaning. Historians believe that the final disaster happened shortly thereafter, after which transformed the level of Sheba in a desert. Some scientists say that the last dam burst 542-570 or 572 took place. Under this new dam failure under remained a repair, after which the cultivated land quickly quilted and Marib was finally abandoned. Others tend to accept this for the seventh century. The Qur'an mentions the spill in Sura 34 " Saba " verse 15 The loss of the dam was different causes attributed, from volcanic activity and earthquakes to be neglect. Robert B. Jansen holds for the latter most likely.
On the economic development of the country in 1986 was built with the support of Abu Dhabi three kilometers above the old dam, a new dam in Wadi Dhanah. This is 760 m long and 40 m high and is 10,000 ha of land with water supply.