Preheat the oven to 375°F.
Unroll the crescent roll dough and separate it into triangles.
On a large baking sheet, arrange the triangles in a circle, overlapping the edges slightly, to form a ring.
Spread the Thousand Island dressing evenly over the dough.
Layer the chopped corned beef, sauerkraut, and Swiss cheese over the dressing.
If using, sprinkle caraway seeds over the cheese.
Fold the points of the crescent dough over the filling, tucking them under the ring to seal.
Brush the top of the dough with the beaten egg.
Bake for 20-25 minutes or until the dough is golden brown.
Let cool for 5 minutes before slicing and serving.
