The Thar Desert ecoregion lies to the west of the Aravalli Mountain Range in the northwestern Indian States of Gujarat, Rajasthan, extending across the border to the Punjab and Sind regions of Pakistan. It is considered to be the 9th largest subtropical desert. The climate is extreme: winter temperatures approach freezing, while summer temperatures soar over 50°C. Rainfall is limited to 100-500 mm from July to September but is very variable. About a tenth of the ecoregion are sand dunes, while the rest is craggy rock formations and compacted salt-lake bottoms. Vegetation has plants adapted to arid conditions including trees and shrubs like Khejri Prosopis cineraria, Balanites roxburghii, Capparis decidua, Euphorbia caducifolia, and Leptadenia pyrotechnica, besides herbs and grasses.