Kain, the name of a sub-province and of a town of Khorasan, Persia. The sub-province extends about 300 m. N. to S., from Khāf to Seīstān, and about 150 m. W. to E., from the hills of Tūn to the Afghan frontier, comprising the whole of south-western Khorasan. It is very hilly, but contains many wide plains and fertile villages at a mean elevation of 4000 ft. It has a population of about 150,000, rears great numbers of camels and produces much grain, saffron, wool, silk and opium. The chief manufactures are felts and other woollen fabrics, principally carpets, which have a world-wide reputation. The best Kaini carpets are made at Darakhsh, a village in the Zīrkūh district and 50 m. N.E. of Birjend. It is divided into eleven administrative divisions:—Shāhābād (with the capital Birjend), Naharjān, Alghur, Tabas sunnī Khaneh, Zīrkūh Shakhan, Kain, Nīmbulūk, Nehbandān, Khūsf, Arab Khāneh or Momenabad.
The town of Kain, the capital of the sub-province until 1740, when it was supplanted by Birjend, is situated 65 m. N. of Birjend on the eastern side of a broad valley, stretching from N. to S., at the base of the mountain Abuzar, in 33° 42′ N. and 59° 8′ E., and at an elevation of 4500 ft. Its population is barely 5000. It is surrounded by a mud wall and bastions, and near it, on a hill rising 500 ft. above the plain, are the ruins of an ancient castle which, together with the old town, was destroyed either by Shah Rukh (1404-1447), a son, or by Baysunkur (d. 1433), a grandson of Timur (Tamerlane), who afterwards built a new town. After a time the Uzbegs took possession and held the town until Shah Abbas I. (1587-1629) expelled them. In the 18th century it fell under the sway of the Afghans and remained a dependency of Herat until 1851. A large number of windmills are at work outside the town. The great mosque, now in a ruinous state, was built A.H. 796 (A.D. 1394) by Kāren b. Jamshid and repaired by Yūsof Dowlatyār.