*2.4. Information Extraction*

We extracted information on key activities, noting down the general processes, times and places of occurrence, and the numbers of starving migrants, or the amount of relief silver and grain. The times in the documents were converted into Gregorian calendar time format with monthly temporal resolution. The locations were recorded based on the current provincial-level and prefecture-level administrative divisions in China.

In the Qing Dynasty, grain was measured in piculs ("dan" in Chinese), and silver used in monetary transactions was measured in taels ("liang"). In the 19th century, 1 picul of rice weighed 60 kg [29]. 1 tael of silver was equal to \$29.6 [44], converted according to the purchasing power of silver at that time.

Firstly, we identified the records of famine-related migration, for example, "(1878) this year, there was a severe drought in Henan, and starving people moved to Xuzhou in search of food [35]" (Figure 3a). Then the migration route was noted down: Henan→Xuzhou.

Secondly, the records of silver and grain allocation were also extracted. "(1877) when the severe drought struck Shanxi and Henan, the central governmen<sup>t</sup> allocated 280,000 taels of silver to Shanxi and 120,000 taels of silver to Henan. Equally, 40,000 piculs of grain from the granaries in Anhui and Jiangsu shall be allocated to Shanxi [34]" (Figure 3b). The silver allocation was noted down: "Beijing→Shanxi, 280,000 taels; Beijing→Henan, 120,000 taels". The grain allocation: "Jiangsu/Anhui→Shanxi, 40,000 piculs". The grain in the paper refers to wheat and rice, the two major food staples in China.

Finally came to the records of social unrest during the famine. It includes revolt, banditry, and insurrection, e.g., "(1878) the bandits rebelled in Shanzhou [34]" (Figure 3c). In this record, the site of the unrest event was the Shanzhou district, which is now the Sanmenxia city of Henan Province.


(**a**) 


(**b**) 

**Figure 3.** *Cont.*


(**c**) 

**Figure 3.** Historical records related to the North China Famine of 1876–1879 (**a**) is from Shenbao, about the famine-related migration; (**b**) is from Qing Shi Lu, about the allocation of money and grain; and (**c**) is also from Qing Shi Lu, about social unrest.
