"A" was the household registration unit in the late Qing Dynasty and the Republic of China. A number of households are organized into one group, which is "one long", which is equivalent to the current village head and village head. Several aces make a guarantee and there is a "guarantee".
Bajia and Sanjia were the eighth and third places in that area at that time, and later evolved into place names. Such place names also have the word "du".