 So, ladies and gentlemen, I would like to introduce you some finds and findings which might be of interest for you, specialist in rock art architecture, though I'm not a specialist in that field. These finds come from Central Sudan, from the Gibralt Sabaloka, which is a small mountain range at the 6 Nile Katarak, some 80 kilometers north of today's Khartoum. In this area, our team is conducting research specialized in prehistory, in Holosimpli history, hunter-gatherers and Neolithic people, and the area or the landscape you can see on the picture, it's a quite arid area today. It's actually a dry savanna, but in early Holosim and part of the Middle Holosim it's been more green. Let's start with the case of Sphinx, it's the site shown on the picture, where we found, beside many other things, we found on the walls of the rocks and immovable boulders, we found circular very, very uniform holes, you can see them on the picture, which must have been drilled, they are clearly artificial. Here you can see some parameters of these holes, you can see they are regular of regular cylindrical shape, they have a uniform diameter about four and a half centimeters, depth is up to 50 centimeters, and I have to say the rock it's a granite, so it's quite hard rock. They are always on vertical rock walls, never on the horizontal surfaces, and at the height up to several meters above the present-day surface. In 2017 we published a reconstruction or the ideas about the function of these drilled holes, because to drill them in the granite background it must have constituted a task of marked difficulty, so it's clear, it means something, it had some function, although we cannot exclude that they may have been created in connection with some rituals or magic action, there is nothing to suggest such an interpretation, it does fall outside the possibilities of factual argumentation and for this reason it is not pursued further in this paper. The fact that the design orientation and distribution of these holes obey certain rules, on the contrary, suggests they were to fulfill some kind of practical function. Directly at the site when documenting the relics we discussed several hypotheses, for instance they were proposed to have constituted remains of pecs to hang objects or ladders and scaffolding known from other sites in North Africa and Sahara and Sahalia. However such use are contradicted by the small diameter of the holes, the inclination and depth and by the lack of reasonable justification for the existence of such fittings at the given particular places. The sole practically acceptable explanation has appeared to be to view the features as the remains of building constructions made of wooden components affixed to the rocks. Let's have a look at the reconstruction, we will look at these two higher, bigger concentrations of the holes found in the northern shelter and 16 in the northern part of the site. So let's start with this one. You see the holes, the colors indicate the depth, four categories, the red ones are the most deep, it's between 30 and 50 centimeters. And the arrows indicate the orientation of the holes. So this is the original level of the terrain before the deflation in the Holocene period, then there is a figure of 175 centimeters. So the idea is that the holes were used to put a pole inside to bend it and to sunk it in the terrain in front of the rock. So this way we get the most fixed and most solid part of the construction, whereas the horizontal ones are just to finish the construction and then you can put whatever cover on it, it can be leaves, it can be matting, it can be leather, whatever. And the construction still is big enough to give place for a standing person inside. This maybe at first sight strange shape is quite logical. You see that the incline of the roof is quite logical because from the northern shelter when the rain comes it's good to drain the rainwater out of the shelter. So this is exactly the position we would expect and even there is a small entrance, it's big like a hide like that, which allows people to enter inside but still it gives the right direction, it means out of the shelter because on the other side there are already the rock walls. This is the other occurrence in the northern part of the site where we have another 16 holes and let's have a look at the reconstruction again to put the vertical poles then the horizontal ones. In this case we suppose it's just hypothetical construction of course the entrance might be in this location or in that one. The latter one fits much much better with the situation in the previous case of the structure one. So just based on the observation and the idea that the main particle or main element was was when the light wooden poles or roots or whatever of wood we came to actually very similar architecture which is known ethnographically from North Africa and you would find that even throughout the world especially at the mobile or semi-mobile societies. These are just examples from the Tuareg communities or rendels on the right side. The logic is still the same, you have a pole just bend it and then you put horizontal elements and then you cover it. Another example from Africa in this case you can see that the house, what is the house that's welling, it's just the place for the bed because other activities are outside the house that's welling. In other cases however there are houses which host more space not only for the bed but for other domestic activities. And just examples of a covers, of a covering like a matting scroll, the very good advantage of this light architecture known from ethnographic evidence is that you just take the poles and put them on the camera or whatever carrier and you can move it anywhere. So it's in this case in ethnographic evidence it's typical for mobile societies. So back to the side the thing is that no one has so far tested this kind of architecture in connection with the rock wall. So this is, if we are right in the reconstruction it means this is some kind of already not existing way of building using the rock walls. As I said it's part of, it can be dwellings because the space is big enough for the construction structural one, it's some 70s, 17 square meters, the other one from it's some 8 square meters. And you can see that people can stand inside so it's quite good. As for the dating at the site of Sphinx we have no idea because it's impossible to date the host directly but we just suggested in the publication 2017 that it's rather from the early Holocene because when the terrain was much higher before it was traded after the secation of North Africa because otherwise the building would be too high for no reason. But it was just an idea without clear dating. Since then we continued, beside many other things, we continued surveying and recording of these holes and you can see in the area of so called Roticides we so far we surveyed all this area after here, this part is still waiting for us. And in here there are thousands of rock walls and immovable boulders we had to run around each singular stone. And we recorded all our occurrences and if you can see all the sites marked here it's Mesolithic sites, it's before 6000 BC. So you can see all the red ones which is the occurrences of the holes nicely fit with the distribution of the sites. Just have a closer look at that, just one example you can see the main areas of the Mesolithic site with the subsidiary ones and among them in the between there are the occurrences of the holes, the identical ones 4 cm in diameter drilled inside the bedrock. Another occurrence, another one. This one is very nice, it's quite close to the site of Sphinx. I showed you the example of the architecture, constructed architecture in this area but since that we collected another evidence from the from the foot of the slows. And there is another one example, this is actually, this is actually you know if you just cut in the middle of this construction, do you connect it to the rocky habit? So clearly in our view this find which you didn't know before clearly confirms the idea of of a huts, a joint fixed to the rock walls. However many other holes you cannot interpret in this way as it remains of many houses. So in this case where you find grinding holes just in front that these are Mesolithic ones, you have no idea what what what they what they functioned was but we are thinking maybe shades, you know to prolong the shade of the stone for the whole day. But it's just it's very difficult you know to interpret. In many other cases we have no idea. In cases like this, for us it makes no sense in a practical sense, maybe it just it was a game we don't know, maybe there was some constructions we cannot just imagine. So this is still waiting for interpretation for anyone, not only us. So let me just conclude. There is only one common denominator of the drilled holes found at Zabaloka. The need to fix a light pole construction to an immovable rock be it for dwelling or other kinds of constellations. Some of them are located directly within the early early Holocene habitation areas. Others come from working zones that are devoted to grinding on the peripheries of the early Holocene sites and the rest of them simply occur in close vicinity of the first Since the holes were drilled into hard granite rocks, it is very probable that the makers have envisaged long into the future function of these elements. So it wasn't just for one time it presupposes they plan to come back to the site or they or it can suggest even continuous stay at the site. On the site let me just add that for the effectiveness and at the same time simplicity we can assume the use of such anchoring elements also in much later periods. This is so not only in Mesolithic. This is indicated by the finds of nearly identical holes drilled into the walls of historical monumental buildings such as in this case Musalata Sufa. We contacted many specialists doing surveys in rocky areas in Sahara and in other parts of the world and also specialists in ancient architecture from the division and asked them do you know such a hole? No one had the idea like they didn't know that. But they're only looking at the pictures. This is just a picture taken by accident during our visit on the site. Just something which no one knows or maybe because no one was thinking about the function of this they are just omitted in publications and they are not recorded even. But I think it's worth it. So as for the significance our aim was to bring to the notice quite an archaic but so far unknown form of mixed constructions in which rocks first had a stabilization with this anchoring function and second in case of dwellings they found part of the structures on one or more of their walls. With the view to the dating of these constructions in the subaloka mountains to the early Holocene we may be touching the very beginnings of artificial modification of rocks with the aim to adapting them to practical functions. At subaloka the basic technological principle was combination of stable and enduring elements that is drilled holes holes of certain parameters and distribution and on the other hand light and easily decaying wooden poles which were easy to replace with low cost. In any case the above presented type of artificial features on rocks or boulders extends the spectrum of constructions whose identification by means of surface field survey or excavation of archaic deposits is quite difficult or especially in other regions with heavily deflated terrains no longer possible. Thank you for your attention.