From this point to the sea the frontier separates Persian territory from British Baluchistan and runs south-east to Kuhak and then south-west to Gwetter.
On the opposite side of the river, in addition to the cultivated portions of the bank, there is a large tract extending from south of Kuhak, or the Seistan dam (band), to the gravelly soil below the mountain ranges which separate Seistan from Baluchistan and Narmashir.
Between the Kuhak band and Rudbar they are mainly Baluch.
They are diverted by means of a large band or dam, known indifferently as the " Amir's," the Seistan " or the "Kuhak " band, It is constructed of horizontally laid tamarisk branches, earth and perpendicular stakes, and protected from damage by a fort on the left and a tower on the right bank of the river.
When the British arbitrator appeared on the scene in the beginning of 1872, though compelled to admit the shah's possession of what has been called " Seistan Proper," he could in fairness insist on the evacuation of Nad Ali, Kala Fath, and all places occupied on the right bank by Persian troops; and furthermore he left to the Afghans both sides of the river Helmund from the dam of Kuhak to its elbow west of Rudbar.