A Czech military jet headed to Mongolia Tuesday with four special passengers — rare wild horses.

The Prague Zoo sent the Przewalski horses on their 6,000 kilometer journey as part of the zoo's effort to reintroduce the endangered animals to their native habitat.

Upon arrival in the Mongolian capital of Ulan Bator, they will be trucked another 280 kilometers to a western reserve.

Przewalski horses are smaller than regular domestic horses and can be identified by their short erect manes.

Hunters along the Chinese-Mongolian border shot the horses to extinction in the wild in the 1960s. Experts used breeding herds in European zoos to reintroduce them to their natural lands.