At the risk of somewhat of repetition, we must here point out the few grand features which diversify this sea of sand, and after defining the difference between _rui_ and _thal_, which will frequently occur in the itinerary, at once plunge _in medias res_. =The Lost River of the Desert.=—We have elsewhere mentioned the tradition of the absorption of the Ghaggar river, as one of the causes of the comparative depopulation of the northern desert. The couplet recording it I could not recall at the time, nor any record of the Sodha prince Hamir, in whose reign this phenomenon is said to have happened. But the utility of these ancient traditional couplets, to which I have frequently drawn the reader’s attention, has again been happily illustrated, for the name of Hamir has been incidentally discovered from the trivial circumstance of an intermarriage related in the Bhatti annals. His contemporary of Jaisalmer was Dusaj, who succeeded in S. 1100 or [295] A.D. 1044, so that we have a precise date assigned, supposing this to be _the_ Hamir in question. The Ghaggar, which rises in the Siwalik, passes Hansi Hissar, and flowed under the walls of Bhatner, at which place they yet have their wells in its bed. Thence it passed Rangmahall, Balar, and Phulra, and through the flats of Khadal (of which Derawar is the capital), emptying itself according to some below Uchh, but according to Abu-Barakat (whom I sent to explore in 1809, and who crossed the dry bed of a stream called the Khaggar, near Shahgarh), between Jaisalmer and Rori-Bakhar. If this could be authenticated, we should say at once that, united with the branch from Dara, it gave its name to the Sangra, which unites with the Luni, enlarging the eastern branch of the Delta of the Indus.[8.1.11] =The Lūni River.=—The next, and perhaps most remarkable feature in the desert, is the Luni, or Salt River, which, with its numerous feeders, has its source in the springs of the Aravalli. Of Marwar it is a barrier between the fertile lands and the desert; and as it leaves this country for the _thal_ of the Chauhans, it divides that community, and forms a geographical demarcation; the eastern portion being called the Raj of Suigam; and the western part, Parkar, or beyond the Khar, or Luni.[8.1.12]