We have identified a group of over 40 people who match at the same place on chromosome 5. The matches usually range from 10-25 cMs with one match to me being 47. About half of the matches start at about 145 and run into the 160s. The shorter matches start around 152-156 and run to 166.
There is only one common known ancestor within the group (late 1700s in New York). Most of us have no idea how we might be related. At last two in the group are Australian and have only English and Scottish ancestry. After checking several GEDCOMS, I have found three that go back to two of my ancestral lines - the Seamans and Jacksons of Hempstead, Long Island in the late 1600s. These two families intermarried a lot and I don't think anyone has sorted them out.
Long Island or Connecticut seems to be the origin of the American branch but the Australians must stem from the English origins.
Isn't it unusual for so many people to share such a large segment so far removed from the common ancestor?