A new study chronicles how central Asia dried out over the last 23 million years into one of the most arid regions on the planet. The findings illustrate the dramatic climatic shifts wrought by the ponderous rise of new mountain ranges over geologic time.Researchers have long cited the uplift of the Tibetan Plateau and the Himalayan Mountains around 50 million years ago for blocking rain clouds’ entry into central Asia from the south, killing off much of the region’s plant life.