It is estimated that the Sichuan Basin and Chongqing area are responsible for about 70 percent of China's total rabbit meat consumption.[7] Yoghurt, which probably spread from India through Tibet in medieval times, is consumed among the Han Chinese. This is an unusual custom in other parts of the country. The salt produced from Sichuan salt springs and wells, unlike sea salt, does not contain iodine, which led to goiter problems before the 20th century.[4]