What disease did all those people in the White Deer Plains die from

It is said to be the prototype of the plague in the novel.

The Tiger Plague of the 21st year of the Republic of China

In the 21st year of the Republic of China (1932), there was a cholera epidemic in Guanzhong and most of northern Shaanxi. This epidemic began on June 19th from a resident of Tongguan, from east to west quickly spread to Xi'an, and then quickly spread to the whole of Shaanxi Province in the east, west, northern Shaanxi, and part of southern Shaanxi Province, day after day, resulting in a large number of deaths of the people.

September, the cholera epidemic has spread throughout the Guanzhong Huaxian, Huayin, Lintong, Weinan, Dali, Chaoyi, Heyang, Pucheng, Chengcheng, Hancheng, Baishui, Fuping, Yaoxian, Chunhua, Linyou, Lantian, Chang'an, Gao'an, Sanyuan, Chiyang, Longxian, Qianxian, Zhouzhi, Toushixian, Binxian, Wugong, Fenghuang, Yongshou, Liquan, Xianyang, Changwu, Qishan, Baoji, Fufeng, Xingping; North Shaanxi Fuxian, Yijun, Fugu, Huangling, Qingjian, Jiaxian, Anding, Yanchuan, Yulin, Wubao, Hengshan; as well as southern Shaanxi Shangxian, Shanyang, Luonan and other 57 counties and Xi'an city. Among them, Huaxian, Huayin, Weinan, Chaoyi, Heyang, Pucheng and Tuxian in Guanzhong are the most serious.

According to newspaper reports at the time: Tongguan County, more than 90 people died in one day on July 4, the Yellow River stopped crossing, the county was horrified! Huayin and Pucheng counties both had more than 10,000 deaths by August 24th. Huaxian County to August 7 deaths of more than 10,000 people. Weinan had more than 1,000 deaths per day in mid-August. Everywhere else there were large numbers of deaths every day, and even the city of Xi'an, which had better medical facilities, had 54 deaths in one day on August 9th. The province*** counted 140,000 deaths.