"Jiangshi, sometimes called "Chinese vampires" by Westerners, are corpses that are usually reanimated due to magical reasons. In ancient China, people always had the preference of being buried in their hometowns, and when a person dies in a land that is not their hometown, their family members hire a sorcerer to bring back their deceased family member. The family commissions the sorcerer in their village to travel to the place of the person's death, locate the corpse, and to write a spell and stick it upon the corpses's face, in which the spell-paper contains their name, birthdate, and some other words to reanimate the corpse. Once the paper is stuck upon the corpses's face, the newly created jiangshi would follow the sorcerer by hopping around, in which the sorcerer would lead it back to its hometown for burial (this was often a last-resort choice used by families with not enough money to hire a cart to carry the corpse back). Usually, the sorcerer would travel by night, and would at least have around three jiangshi traveling with it. But when the written spell-paper falls or is pulled off of the jiangshi (in the case the sorcerer is not paid the agreed amount for his doings, he might rip off the jiangshi's spell-paper), it gains its own consciousness, and all the power that the sorcerer formerly had over it would be lost. Instead of being an obedient corpse that followed the sorcerer, the jiangshi would be rampant and dangerous. The freed jiangshi would begin killing living creatures to absorb life essence (qì) from their victims. They are said to be created when a person's soul (pò) fails to leave the deceased's body."

Via Wikipedia:
https://en.wikipedia.org/wiki/Vampire_folklore_by_region#Asia