Hundreds of prehistoric “cult sites” celebrating sex and death have been found in the Eilat Mountains, a very dry area of Israel’s Negev Desert. It is not the subject of the sites that make them mysterious however. It is the sheer number of them, their location and the lack of habitation sites that accompanies them.

The sites, dated to around 6,000 BCE, contain a variety of artifacts and structures. Common to the sites are stone circles measuring 5 to 8 feet wide with penis shaped carvings pointing toward them. Many sites also contain standing stones, human carvings and stone bowls.

Sex and death are common themes in the history of human religion and appear to have been the central concepts behind this one.

In addition to the penis shaped structures, some sites have stones with vulva shaped holes cut into them. Researcher believe that the circles that the penis shaped structures point to are also female symbols.

“The circle is a female symbol, and the elongated cell is a male one (phallus),” Uzi Avner, a researcher with the Arava-Dead Sea Science Center and the Arava Institute, told Live Science.

The placement of the sites also appears to be significant. The archeologists report that the sites tended to be in flat areas of the mountains with a commanding view.

“Their position on topographic ‘shoulders’ or comparatively flat locations probably enabled several dozens of people to gather around them, for example, an extended family. Commonly, a broad view is seen from the sites, so possibly, the scenery was one element in the selection of their location,” the team wrote, in the Journal of the Israel Prehistoric Society.

According to the paper, death at the sites is “signified by the burial of stone objects and by setting them upside down.” At one site a stone carving in the shape of a human was also buried. Researchers also found evidence of animal sacrifice at the sites.

Whatever the sites were for, the adherents to the ancient religion apparently believed that it was important to have a large number of sites. In one 200 acre area the team discovered 44 separate sites.

“Taking in[to] consideration the topography, environmental conditions and the small number of known Neolithic habitations in the general southern Negev, the density of cult sites in this region is phenomenal,” wrote the researchers.

Given the environment of the area it is not surprising that there was little sign of habitation. The region is arid desert, receiving less than an inch of annual rainfall. It is believed that, when the sites were active it was somewhat wetter but not enough to have encouraged habitation.

“The climate of the 7th-6th millennia B.C. was a little moister than that of the present, 40%-20% more rainfall, but the desert was a desert,” said Avner.

In total the team found only three habitation sites in the region, all of which seemed to be associated with religious sites.

“In contrast to the density of cult sites, only two small habitations and one small campsite were found on the ridge,” they wrote, noting that these three sites were all associated with the cult sites.

In addition to the 100 sites studied to date, a survey of the area has yield an additional 349 sites awaiting excavation.

“The number of cult sites recorded to date suggests that many more still await discovery. Many more may be found on the mountains of the Negev, southern Jordan and Sinai,” said the team.