Final answer:
The Mongolian military advantage attributed to their nomadic lifestyle is their superior horsemanship and mobility.
Step-by-step explanation:
The Mongols were skilled horsemen who had been on horseback since childhood and could fire arrows while galloping. They had access to multiple horses and could switch between them, allowing them to cover large distances quickly. This nomadic lifestyle also made them adaptable and resourceful, as they had no supply train and could rely on their horses for food and transportation.