Perched on the left side of the sleigh, his legs firmly planted on a runner, Nyadma Khudi raps the backs of his reindeer with a tyur—a long pole of polished wood ending in an antler knob.

Every year on Christmas Eve, nine reindeer pull Santa’s sleigh through the sky so he can deliver presents to children throughout the world. Their names are Dasher, Dancer, Prancer, Vixen ...