The entrance to a Bronze Age winter camp (IMAGE) University of Sydney Caption North-western Xinjiang: the entrance to a Bronze Age winter camp. The gaps between the parallel lines of stones were filled with packed mud to provide thick wind-proof protection from blizzards. Credit Alison Betts Usage Restrictions Only for use with this story and only with credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.