Further description (in the 29th chapter) contains very few landmarks and a lot of contradictions. Yes, Rubruk noted:
Proceeding thence three days we came to the head of that province, at the head of the said sea […] And we saw a big island in it […] tasted the water, which was brackish, though drinkable. There opened a valley which came from out high mountains in the south-east, and there amidst the mountains was visible another big sea, and a river came through that valley from that sea into the first one […] So we crossed this valley, following a northerly direction towards great mountains.
What does "head of that province" – any commentator could not explain, and I also can not explain it. Definitely, that was not the city. "The said sea" in the comments by N.P. Shastina "probably Alakol" (this accepted in english translation too). It is indeed tempting assumption because the south-east of Alakol really stretches the valley between the ridges Dzungarian Alatau and Maylitau. This valley is called Dzungaria gate, and on its south-eastern end is a Aibi lake, which would be Rubruk's "another sea". I think that assimilation was served as one of the reasons for preferring the northern route, although it obviously was not written anywhere.
However, this interpretation has its own difficulties. First, Rubruk, writing about "the said sea", obviously meant Balkhash, and secondly, any river in Dzungarian gate is not flowing – the western part of the valley belongs to the Alakol lake basin, and east – to Aibi lake basin. Thirdly, Lake Alakol not saltish but still pretty salty.
Therefore, I propose to consider another variant of the route: leaving from Cailac (Ghulja), travelers crossed through the Borohoro ridge and down to freshwater Sayram lake (it should be noted that modern highway connecting the Ghulja with other areas of China, although passed by Sayram lake, perhaps this way had some microgeographical benefits, which made use of modern road builders). Further valley from this lake to the Aini lake stretches to the east, and again there is no river, which would be connecting these lakes.
Further Rubruk's route completely devoid of landmarks. On the way to Möngke's court he twice wrote: "We going in a northerly direction" and does not mention the movement to the east, and yet his general course it was just to the east. So I assume that from the area of Aibi lake (200 km from Ghulja) travelers moved eastward along the northern foothills of the eastern Tian Shan (700 km to the valley between the mountains Baytag-Bogdo-Nuru in the north and Kekserke the south. It is possible that here was "certain place amidst most terrible rocks", where Rubruk drove away devils by his prayers, but there are a lot mountains in the area…). Then they drove steppes, which are called Dzungarian Gobi (350 km) and Trans-Altai Gobi (400 km to the lake Khara-Tolgoyn-Khuduk). So I think their way passed between two major mountain systems – Mongol Altai in the north and eastern Tien Shan in the south.
To determine the final section of the route, we need to localize Möngke's headquarters. To our happiness, Rubruk gave two "bearings" for this (Ch. 39):
And I questioned priests, who had come from Cathay, who bore witness to it, that from the place where I had found Mangu Chan to Cathay was twenty days journey between south and east; while to Onan Kerule, which is the true country of the Mo'al, and where is the ordu of Chingis, was ten days due east.
Since I am not a historian, but physicist (the former…) then to interpret these data, I am armed with a map from Google:
Place of Möngke's headquarters in Mongolia
Figures on the map is marked:
1 – Ulan Bator, the present capital of Mongolia, from which we are paying a distance;
2 – a distance of 225 km to the east (and slightly to the south) leads to the center of "land of Mongols";
3 – "land of the Mongols" (a square with side 150 km);
4 – a distance of 325 km of the modern highway road to the south (and slightly west) from Ulan Bator (to Khuld village in the Dundgovi province);
5 – a distance of 325 km to the west (and slightly to the south) from Ulan Bator leads to Karakorum;
6 – Karakorum;
7 – 400 km radius of the arc drawn around the center of "the land of Mongols";
8 – Yinchuan city, located in the place where the Great Wall of China crosses the Yellow River, south and east of it lies Cathay;
9 – 800 km radius of the arc drawn around Yinchuan;
10 – that is happiness: a meeting place near Khuld can not be changed;
11 – possible way of Möngke's court to Karakorum.
Onon and Kherlen in the upper flow runs almost parallel at a distance of 120..150 km. If we assume that the real land of Mongols is a square with side 150 km between the tops of these rivers (marked on map by number 3), it will appear the center point somewhere 47° 30' North latitude, 110° East longitude. This point is about 225 km east of Ulan Bator (line 2 on the map). We put at this point compass and draw the arc of 400 km radius (curve 7 on the map).
Next, we assume that Rubruk's Cathay is a territory south of the Great Chinese Wall (long and well marked visual border). At this border city Yinchuan choose conditionally (on the map marked number 8), which lies near the Yellow River in the place where the Great Wall of China crossed the river. Circumscribe an arc of 800 km radius (indicated by figure 9).
Intersection zone of our arcs covers the Dundgovi province and part of Dornogovi province in Mongolia. This is the locus of points (we learned in high school and remember geometry, is not it?), which satisfies the conditions of Rubruk's bearings.
We choose the most western point and enters to the region of Khuld settlement (map marked number 10, its coordinates – 40° North latitude, 105° 30' East longitude). That is, in our opinion, place were Rubruk meet Möngke's court. It is 400 km east of lake Khara-Tolgoyn-Khuduk. A total way from Ghulja was approximately 2050 km, covering on average 71 km per day. In general, this rate is consistent with Rubruk's record that he was driving two postal stations (iam) each day, distant from each other on the day of the way (hence this transition was about 35 km). This courier speed required to move at night because the short winter day was not enough.
Consider the weaknesses of this building.
1. The direction of movement of Cathay in our scheme – just to the south, not south-east, as Rubruk noted (southeast of the point we found the Cathay as the whole country, but not as a specific place to which the 20 days the way).
2. The direction of movement to the land of Mongols – northeast, not east, as in Rubruk.
3. Location of Mongols' land at the top of the Onon and Kherlen seems arbitrary. What prevents to move it further to the northeast, as interfluve extends for 600 km? But if we move it further down, the arcs of our building will no longer intersect. For these reasons, we must move the Mongols' land to the west as far as possible.
4. Why as a reference point for Cathay selected Yinchuan? Why one can not select a point which lies to the west or east of this city?
Great China Plain is a generally rectangular, north side of which outlined the Chinese wall, and west – Highlands Kunlun. Yinchuan city indicates the northwestern corner of the rectangle. Great Wall of China stretches from it to the west for another 600 km, but there it limits the narrow strip of land (50 – 100 km in width), having Nanshan ridge to the south. Clearly it is not a big country, which was Rubruk's Cathay. In addition – at the early 13th century this strip of land belonged to the Tangut state (Western Xia); Rubruk knew Tanguts well and clearly distinguished from real Chinese. All this makes it impossible to move this basic point further west. In addition, when trying to move this arc will no longer build our cross, and the direction changed to south-west (instead of south-east).
Against the movement of the base point to the east along the Great Wall can not be such decisive objections. While do so arcs intersection zone moves eastward too. For example, if we take the base point for the city Yulin in Ordos (located near the Great Wall, 250 km east of Yinchuan), the zone of curves intersection shifts to the east about 100 km. The direction to China will remain southern, and the direction to the Mongols' land will change to the north (that is move away more from the recorded by Rubruk).
5. Arcs intersection zone stretching from west to east about 500 km, why it selected the western point of the zone? But if we try to choose the extreme eastern point of the zone, the direction to the Mongols' land will become the north-west, and to China – the south-west.
Having considered all the objections as a whole, we must admit that selected by us location of Möngke's court minimizes all complications, although not eliminate them completely. Of course, I realize that it is impossible to calculate the location of objects in the desert to within 1 km – is 50 km, but with such tolerances proposed route is consistent with the data source.
Together with Möngke's court Rubruk almost two months (until mid- February) traveled to the south, and then after another two months of slowly movement northward arrived in Karakorum – the only feature in central Asia, for which there is no doubt of identification and location.
With the stay in Mongolia associated another Rubruk's geographic enigma. There is location on the map of nations Longa, Solanga and Muc. In comments by N.P. Shastina said that Longa and Solanga should be Koreans, and Muc – "people Mokhe, or Mokho, tribes of Tungus origin who inhabited the valley of the Amur and Ussuri and engaged argiculture and cattle".
All this sounds very hollow. The sequence of descriptions in Chapter 28 is: Uighurs – (further east) – Tanguts – (further south) – Tibetans. About Longa and Solanga told that they live "beyond Tibet". Rubruk wrote it staying in Mongolia, and from this position place after (behind) Tibetan people is further south. And behind them, that is further south living Muc people. Rubruk noted that there were cities in Muc land (well, on the Amur and Ussuri there were no cities until the early Russian colonization). Therefore on the maps I put these peoples south of the Tibetans. Longa and Solanga in this case may be people of southern Tibet or modern southern China, and Muc – perhaps, Burma (kingdom Pagano 11 – 13th cent., which had a lot of cities and temples).
The Mongols under the command of Prince Kublai, as we know, in 1253 conquered Yunnan in southern China (actually, the Kingdom of Dali) and then, presumably, searched a way to Burma, where they took campaigns in 1277 and 1287, respectively. So I think that this Rubruk's piece recorded after the words of master William, built on the report from Kublai campaign in 1253.