The Carpatho-Rusyn Society is a non-profit society which supports the Carptho-Rusyn ancestry in the United States and East Central Europe.
“There is still much debate by scholars regarding the origins and early history of the Slavic people. What is agreed upon is that Slavic people have lived in the Carpathian region as early as the sixth century AD. The Carpatho-Rusyns are the direct descendants of one of these Slavic tribes that has lived along the Uz River called the White Croats (Bilyj Horvaty). By the 900s, waves of Slavic settlers calling themselves Rus’ came from the East and began settling into the Carpathians, intermarrying and assimulated with the White Croats. From the Kievan Rus’ kingdom they adopted their national name of “Rusiny,” meaning — the inhabitant or descendant of Rus’. In time it became the common name of all southeastern Slavic tribes from the Poprad River in Prijasevska Rus’ all the way to the Caspian Sea and the River Don.
Since many Rusyns lived for centuries under Hungarian rule, they were often called Uhorsky Rusyny, Rusyns of Hungary. After World War I, they were called from their habitat “Podkarpats’ky Rusyny,” Rusyns living under the Carpathians. Those living in the Polish kingdom (later Austria) were called Rusnaky and later, Lemkos.”
This site has helpful information on genealogy, publications, and traditions for people with Slavic, Rusyn, and Lemko ancestry.