If you're descended from Irish Vances, you should know of William Balbirnie's book; a genealogy of Vances in Ireland in 1860 and listed on our Online Books of Interest page. While it certainly contains errors (and it's not really a primary source, so you need to take it with a little skepticism), his book is still the best available source of detail about Irish Vances in Ulster from 150 years ago and so has been referenced for decades by Vance researchers looking to tie their family trees back to Ireland.
Balbirnie lists dozens of places in Ireland where Vance families lived or were known to have lived in the past. Many of these placenames were Gaelic in origin and their written names in English have changed over the years, even from Balbirnie's day to modern times. But because of these and other changes across the landscape of Northern Ireland, many of these places are hard to find on a map today.
I made the map below for a book on the older Vance lines and I thought it might be useful to anyone else researching Vance lines in Ireland (credit for the map image, by the way, goes to JPL/Caltech, and the mapping tool was Google Earth (TM) - both of whom require attribution!).
You'll find a table of details for each location, with Google Earth(TM) lat/long references and comments where appropriate ("WB" in the table means "William Balbirnie"). You'll see a confidence assessment too - for example Balbirnie mentions the will of Patrick of "Lifficulty" in 1697, but that place appears nowhere in modern or old books about Ireland. However, the modern transcription of the Index to Raphoe Wills lists the same will for Patrick of "Lissacully", and there IS a modern "Lissacholly" in Donegal. Is it the same place? It seems the best fit, but I listed it with lower confidence and I'm happy to be corrected if anyone has a better answer.
There are two more detailed views where the larger map gets densely crowded and hard to see. Click on these pictures below for larger versions.
Hope this helps anyone looking to find the path of their Vances in Ireland!