Though most all Yanceys/Yancys descend from
a common group of families of early Colonial Virginia - there is at least one
of a group of Yanceys that descend from one Peter Jensen/Yensen of Denmark who came to America sometime probably in the 1860's and settled in St Francois County, Missouri.
Some of his descendants began to use the spelling of YANCEY instead of Yensen.
(Note a Danish person would pronounce a "J" like we pronounce a "Y" )
There is no reason to believe the two different Yancey families are in any way related.
Below is an 1880 census file of the family followed by a group of obituaries of member of this family.