Thar Desert natural vegetation of this dry area is classed as Northwestern thorn scrub forest occurring in small clumps scattered more or less openly. Density and size of patches increase from west to east following the increase in rainfall. The natural vegetation of the Thar Desert is composed of the following tree, shrub and herb species: The endemic floral species include "Calligonum polygonoides", "Prosopis cineraria", "Acacia nilotica", "Tamarix aphylla", "Cenchrus biflorus". The Thar Desert is the most widely populated desert in the world, with a population density of 83 people per km. In India, the inhabitants comprise Hindus, Muslims, and Sikhs. In
Twilight in the Desert favor. Similarly themed books include: Twilight in the Desert Twilight in the Desert: The Coming Saudi Oil Shock and the World Economy is a book by American investment banker Matthew Simmons. The text was initially published on June 10, 2005 by John Wiley & Sons. The book focuses on the petroleum industry of Saudi Arabia and posits that this country is approaching—or already at—its peak oil output and cannot substantially increase its oil production. —Review on theoildrum.com Simmons' prediction of rising oil prices made in "Twilight in the Desert" led to a bet with "New York Times" columnist John Tierney