"The real question is, 'How great was Greater India?'"

Jagoutz asked. "If you know when India hit, you know the size of Greater India," he said. By dating the Indian-Eurasian collision to 10 million years later than previous estimates, Jagoutz and his colleagues conclude that 'Greater India' must have been much smaller than scientists have thought. Since 2000, Jagoutz has trekked to the northwest corner of the Himalayas, a region of Pakistan and India called the Kohistan-Ladakh Arc. This block of mountains is thought to have been a string of islands that was sandwiched between the two continents as they collided. Jagoutz carved out rock samples from the region's northern and southern borders and his team has brought back three tons of rocks, which he and his colleagues analysed for signature isotopes. The evidence supports a new timeline of collisional event according to which 50 million years ago, India collided with a string of islands, pushing the island arc northward. Ten million years later, India collided with the Eurasian plate, sandwiching the string of islands, now known as the Kohistan-Ladakh Arc, between the massive continents. "If you actually go back in the literature to the 1970s and 1980s, people thought this was the right way," Jagoutz said. "Then somehow the literature went in another direction, and people largely forgot this possibility. Now this opens up a lot of new ideas," he said.