In Hellenistic and Roman Arabia and Egypt, a hydreuma (plural hydreumata) was an enclosed (and often fortified) "watering station" (Greek hydros, "water") at wadi

Wadi

Wadi is the Arabic term traditionally referring to a valley. In some cases, it may refer to a dry riverbed that contains water only during times of heavy rain or simply an intermittent stream.-Variant names:...

s in dry regions. A hydreuma was a manned and fortified watering hole or way station along a caravan route, providing a man-made oasis

Oasis

In geography, an oasis or cienega is an isolated area of vegetation in a desert, typically surrounding a spring or similar water source...

. Juris Zarins, rediscoverer of the city of Ubar in Arabia, described that site in a 'Nova' interview:

"The site that we uncovered at Shisur was a kind of fortress/administration center set up to protect the water supply from raiding Bedouin tribes. Surrounding the site, as far as six miles away, were smaller villages, which served as small-scale encampments for the caravans. An interesting parallel to this are the fortified water holes in the Eastern Desert

Eastern Desert

The Eastern Desert is the section of Sahara Desert east of the Nile River, between the river and the Red Sea. It extends from Egypt in the north to Eritrea in the south, and also comprises parts of Sudan and Ethiopia.-Features:...

 of Egypt from Roman times. There, they were called hydreumata."

In the 1st century CE, Pliny's Natural History described the current Roman sea-route to India, which had recently been established. The Via Hadriana

Via Hadriana

The Via Hadriana was an ancient Roman road established by the emperor Hadrian, running from Antinopolis to the Red Sea at Berenike. It was finished in 137 AD...

, the route that linked the Nile

Nile

The Nile is a major north-flowing river in North Africa, generally regarded as the longest river in the world. It is long. It runs through the ten countries of Sudan, South Sudan, Burundi, Rwanda, Democratic Republic of the Congo, Tanzania, Kenya, Ethiopia, Uganda and Egypt.The Nile has two major...

 with the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

, was established by hydreumata. The annual caravan from Alexandria sailed up the Nile to Keft (Pliny's Coptus).

"From Keft the journey is made with camels, stations being placed at intervals for the purpose of watering; the first, a stage of 22 miles, is called Hydreuma; the second is in the mountains, a day's journey on; [103] the third at a second place named Hydreuma, 85 miles from Keft; the next is in the mountains; next we come to Apollo's Hydreuma, 184 miles from Keft; again a station in the mountains ; then we get to New Hydreuma, 230 miles from Keft. There is also another old Hydreuma known by the name of Trogodyticum, where a guard is stationed on outpost duty at a caravanserai accommodating two thousand travellers; it is seven miles from New Hydreuma. Then comes the town of Berenice where there is a harbour on the Red Sea, 257 miles from Keft."

The site of the "Hydreuma of Apollo", Apollos Hydreuma, mentioned by Pliny has yielded papyri

Papyrus

Papyrus is a thick paper-like material produced from the pith of the papyrus plant, Cyperus papyrus, a wetland sedge that was once abundant in the Nile Delta of Egypt....

 in modern times. The hydreumata of Abu Qreiya and of Samut have been surveyed but not excavated. Abu Qreiya, one of these watering places, consists today of a concrete well in the wadi, drilled at the beginning of the 20th century; Aby Qreiya has been surveyed but not excavated.

Another route dictated by hydreumata dug into the beds of wadis linked the barren mountain that was the sole source of Roman "imperial porphyry

Porphyry (geology)

Porphyry is a variety of igneous rock consisting of large-grained crystals, such as feldspar or quartz, dispersed in a fine-grained feldspathic matrix or groundmass. The larger crystals are called phenocrysts...

" with the Nile, the Via Porphyritis, the Porphyry Road.

Along the way are seven hydreumata, or fortified wells, each one a day's march from the next. Outside the fortifications are lines of large stones to which oxen were tethered at night." (Werner 1998).