Horcrux antecedents.

[Bruce Alan Wilson]

No: HPFGUIDX 155187

Lupinlore:
"(For non-D&D people, a lich is a very powerful and evil wizard who 
insures immortality by storing his soul, or a part thereof, in an 
object called a phylactery. He thus becomes a very dangerous kind of 
undead and essentially unkillable unless you can get your hands on the 
object he's stored his soul in. But you have to be careful, because 
those pesky evil wizard souls have a way of invading people's minds 
and taking up residence. Sound familiar? :-))"

BAW:
The theme of placing one's soul (or heart, or life-force) in an external object that must be destroyed before you can be killed is a common motive in Slavic folklore.  Think of the Firebird, where Koeschi's soul is inside an egg inside a duck in the middle of an inaccessible lake.  There are other examples, but that is the one that comes to mind.

BAW