Coahula, Or Colialmila, a state of Mexico, between lat. 24° 17' and 29° 43' N, and lon. 100° and 103° 30' W., bounded N. and N. E. by Texas, from which it is separated by the Rio Grande, E. by Tamaulipas and Xuevo Leon, S. by Zacatecas, and W. by Durango and Chihuahua; area, 58,920 sq. m.; pop.in 1809, about 96,000. The surface is rough, being intersected by several ranges of mountains which traverse it from N. W. to S. E. The only plain of any extent is in the W. part, and is called the Bol-son (sack) de Mapimi, from the peculiar manner in which it is enclosed, having no opening excepting on the north. Several tribes of savage Indians overrun this plain, to the serious detriment of the farmers and miners. Villages and farms once prosperous have been abandoned in many instances by their inhabitants, as the only means of escaping their ferocity. A large part of the remainder of the state consists of rough mountainous country, and desert plains without wood or water; but there is much good grazing land, and except for the insecurity consequent upon the proximity of the savages, cattle might be extensively raised.

In the Bolson de Mapimi are Lakes Mapimi or Caiman and Parras. The river Mapimi flows into the former, and the Rio Grande del Parras into the latter; both are small streams. The Salada, Sabinas, Toya, and Meteros, all affluents of the Rio Grande, are inconsiderable. Silver mines exist in the mountains, but few are worked on account of the lack of sufficient capital and hands, and the depredations of the Indians. The land adapted for tillage is limited, but when quietly possessed is well cultivated and yields abundantly. The chief cereals are maize, wheat, and barley. In the S. part the maguey (agave Americana) is cultivated in large plantations. Parras and its vicinity are famous for their vineyards and the excellent quality of their wine. Brandy of high repute is also manufactured in considerable quantities. There are some large landholders in Coahuila, who would be very wealthy could their property be protected, but who are comparatively poor in the insecure condition of the country. The wines and liquors already mentioned, with coarse cloths and pottery, form the only manufactures; and the exports consist of wines, wheat and other grains, mules, horses, buffalo tongues, ox hides, deer skins and horns, wool, silver, iron, copper, amianthus, sulphur, and other minerals.

Saltillo in the southeast, on the river Tigre, is the capital. Seven miles S. is the site of the battle of Buena Vista. (See Buena Vista.) The other principal towns are Monclova or Coahuila, Santa Rosa, and Parras.