Mongolian herdsmen often play musun shagai, known as “ice shooting.” Their goal is to send a small copper puck called a zakh down a 93-yard stretch of ice and knock over several cow ankle bones — painted red, none bigger than a golf ball — at the other end. There are extra points for hitting the biggest target, which is made of cow hide. Together, the targets form a line of tiny red dots that are difficult to see, let alone hit. When that happens, the players know at once, because the spectators raise a boisterous cheer.

The players assume a static lunge, digging their back foot into a tiny divot in the ice. They release their zakhs with a throw and a hopeful look. All squint down the river to see if a red target was hit.

Only men play ice shooting competitively, though the event brings whole families together. Children scuttle around the ice in their boots, bundled up for the 20-degree weather.

Musun shagai is a homegrown game, created in the 19th century as a way to pass the time. March and April is the final gaming season before the river melts, the last opportunity to wile away the winter hours before the mayhem of spring.

The frozen surfaces that make this game possible are harder to come by in a warming world. According to data from Mongolia’s Institute for Meteorology, Hydrology and Environment, the country’s annual mean temperature has increased by 2.2 degrees Celsius (nearly 4 degrees Fahrenheit) since data collection began in 1940. (The global temperature increase since 1880 has been 0.8 degrees Celsius or 1.4 degrees Fahrenheit).